Synopsis of the biological data on the leatherback sea turtle (dermochelys coriacea) Biological Technical Publication BTP-R4015-2012

              Synopsis of the
Biological Data on the
Leatherback Sea Turtle
(Dermochelys coriacea)
Biological Technical Publication
BTP-R4015-2012
U.S. Fish & Wildlife Service
Guillaume Feuillet
Synopsis of the
Biological Data on the
Leatherback Sea Turtle
(Dermochelys coriacea)
Biological Technical Publication
BTP-R4015-2012
U.S. Fish & Wildlife Service
Karen L. Eckert 1
Bryan P. Wallace 2
John G. Frazier 3
Scott A. Eckert 4
Peter C.H. Pritchard 5
1 Wider Caribbean Sea Turtle Conservation Network, Ballwin, MO
2 Conservation International, Arlington, VA
3 Smithsonian Institution, Front Royal, VA
4 Principia College, Elsah, IL
5 Chelonian Research Institute, Oviedo, FL
iv Synopsis of the Biological Data on the Leatherback Sea Turtle
Author Contact Information:
Karen L. Eckert, Ph.D.
Wider Caribbean Sea Turtle Conservation Network
(WIDECAST)
1348 Rusticview Drive
Ballwin, Missouri 63011
Phone: (314) 954-8571
E-mail: keckert@widecast.org
Bryan P. Wallace, Ph.D.
Sea Turtle Flagship Program
Conservation International
2011 Crystal Drive
Suite 500
Arlington, Virginia 22202
Phone: (703) 341-2663
E-mail: b.wallace@conservation.org
John (Jack) G. Frazier, Ph.D.
Smithsonian Conservation Biology Institute
1500 Remount Road
Front Royal, Virginia 22630
Phone: (540) 635-6564
E-mail: kurma@shentel.net, frazierja@si.edu
Scott A. Eckert, Ph.D.
Wider Caribbean Sea Turtle Conservation Network
(WIDECAST)
Department of Biology and Natural Resources
Principia College
Elsah, Illinois 62028
Phone: (314) 566-6301
E-mail: seckert@widecast.org
Peter C.H. Pritchard, Ph.D.
Chelonian Research Institute
401 South Central Avenue
Oviedo, Florida 32765
Phone: (407) 365-6347
E-mail: chelonianRI@aol.com
Editor:
Sandra L. MacPherson
National Sea Turtle Coordinator
U.S. Fish and Wildlife Service
7915 Baymeadows Way, Ste 200
Jacksonville, Florida 32256
Phone: (904) 731-3336
E-mail: Sandy_MacPherson@fws.gov
Recommended citation:
Eckert, K.L., B.P. Wallace, J.G. Frazier, S.A. Eckert,
and P.C.H. Pritchard. 2012. Synopsis of the biological
data on the leatherback sea turtle (Dermochelys
coriacea). U.S. Department of Interior, Fish and
Wildlife Service, Biological Technical Publication
BTP-R4015-2012, Washington, D.C.
For additional copies or information, contact:
Sandra L. MacPherson
National Sea Turtle Coordinator
U.S. Fish and Wildlife Service
7915 Baymeadows Way, Ste 200
Jacksonville, Florida 32256
Phone: (904) 731-3336
E-mail: Sandy_MacPherson@fws.gov
Series Senior Technical Editor:
Stephanie L. Jones
Nongame Migratory Bird Coordinator
U.S. Fish and Wildlife Service, Region 6
P.O. Box 25486 DFC
Denver, Colorado 80225
Phone: (303) 236-4409
E-mail: Stephanie_Jones@fws.gov
ISSN 2160-9498 Electronic ISSN 2160-9497
Biological Technical Publications online: http://library.fws.gov/BiologicalTechnicalPublications.html
Table of Contents v
Table of Contents
List of Figures � ix
List of Tables � x
Acknowledgments � xii
Executive Summary ��������������������������������������������������������������������������������������������������������� 1
Chapter 1: Identity � 2
Nomenclature � 2
Valid Name � 2
Synonymy � 2
Type Locality � 3
Taxonomy � 3
Affinities ���������������������������������������������������������������������������������������������������������������������� 3
Diagnosis � 4
Taxonomic Status ����������������������������������������������������������������������������������������������������������� 4
Subspecies � 5
Standard Common Names � 5
Definition of Size Categories � 5
Morphology ���������������������������������������������������������������������������������������������������������������������� 6
Description � 6
External Morphology and Coloration �12
Coloration �13
Eggs �13
Internal Morphology �13
Alimentary System �14
Respiratory System �15
Circulatory System �15
Urogenital System �15
Muscular System �16
Cranial Morphology �16
Skull �16
Post-Cranial Skeleton �17
Cytomorphology �18
Biochemistry �19
Karyotype �19
vi Synopsis of the Biological Data on the Leatherback Sea Turtle
Chapter 2: Distribution �21
Total Area �21
Differential Distribution �24
Hatchlings �24
Juveniles and Subadults �24
Adults ������������������������������������������������������������������������������������������������������������������������24
Determinants of Distributional Changes �25
Hybridization �������������������������������������������������������������������������������������������������������������������25
Chapter 3: Bionomics and Life History �26
Reproduction �26
Sexual Dimorphism �26
Age at Maturity �26
Courtship and Mating �27
Nesting Behavior �28
Emergence from the sea onto the nesting beach �28
Overland traverse to and selection of a suitable nest site �29
Excavation of a body pit �30
Excavation of the nest chamber �30
Oviposition �30
Filling the nest �30
Covering and concealing the nest site �30
Returning to the sea �30
Density-dependence �31
Eggs �32
Fertility ������������������������������������������������������������������������������������������������������������������35
Reproductive Cycles �35
Embryonic and Hatchling Phases �40
Embryonic Phase �40
Embryonic development �40
Embryo abnormalities ������������������������������������������������������������������������������������������������43
Hatching success and sources of embryonic mortality �43
Temperature dependent sex determination �46
Hatchling Phase �47
Hatching and emergence �47
Offshore swim �51
Imprinting and natal homing �52
Juvenile, Subadult and Adult Phases �53
Longevity �53
Hardiness �53
Competitors �54
Predators �54
Parasites and Commensals �55
Abnormalities and Injuries �58
Nutrition and Metabolism �59
Food �59
Feeding �63
Growth �65
Table of Contents vii
Scales �66
Platelets �66
Plastron and extremities �66
Pigmentation �66
Secondary characters �66
Growth rate �66
Metabolism �67
Thermoregulation �70
Osmoregulation �71
Behavior �71
Migrations and Local Movements �71
Satellite telemetry �73
Inter-nesting behavior �76
Navigation and Orientation �76
Diving �79
Schooling �81
Communication �81
Sensory Biology �82
Vision �82
Olfaction �82
Hearing �83
Chapter 4: Population �84
Population Structure �84
Sex Ratio �84
Age Composition �84
Size Composition �84
Phylogeography �85
Abundance and Density �85
Average Abundance and Density �85
Changes in Abundance and Density �86
Natality and Recruitment �87
Reproductive Rates �87
Factors Affecting Reproduction �88
Recruitment �88
Mortality �88
Mortality Rates �88
Factors Causing or Affecting Mortality �88
Direct take �88
Incidental capture �90
Longline fisheries �91
Gillnets and driftnets �92
Pot fisheries �92
Trawl fisheries �93
Regional summaries and general notes �93
International trade ����������������������������������������������������������������������������������������������������94
Marine debris and pollution �94
Other �95
Population Dynamics �96
viii Synopsis of the Biological Data on the Leatherback Sea Turtle
Chapter 5: Protection and Management �97
Conservation Status �97
Legal Status �97
Regulatory Measures �98
Management Strategies ������������������������������������������������������������������������������������������������������99
Gaps and Recommendations � 100
Chapter 6: Mariculture �������������������������������������������������������������������������������������������������� 104
Facility Considerations � 104
Food and Feeding � 105
Literature Cited � 107
Appendix A � 151
Life stages of the leatherback sea turtle, Dermochelys coriacea (photographers in parentheses).
Appendix B � 154
Leatherback sea turtle cranial skeleton: skull dorsal, ventral views. Source: Wyneken (2001:23, 24).
Appendix C � 156
Leatherback sea turtle post-cranial skeleton. Sources: Fretey (1981:21) adapted from Deraniyagala
(1939), and Pritchard & Trebbau (1984:254) with carapace bones (D) adapted from Remane (1936)
and the plastral view of the shell with elimination of remnants of mosaic bones (E) adapted from
Deraniyagala (1939).
Appendix D � 160
Nesting sequence of the leatherback sea turtle. Approach from the sea (Kimberly Maison), site
preparation (“body-pitting”) and nest chamber excavation (Scott A. Eckert), egg-laying (Alicia Marin),
and nesting covering (with measuring) and return to the sea (Carol Guy Stapleton).
List of Figures ix
List of Figures
Figure 1. Global distribution of the leatherback sea turtle, including northern and southern oceanic
range boundaries and sites representative of the species’ current nesting range. Extreme northern
and southern records (see Table 6 for coordinates) may not represent persistent nesting grounds, but
represent known geographic boundaries for successful reproduction. Map created by Brendan Hurley
(Conservation International). �22
Figure 2. Generalized leatherback sea turtle life cycle. Source: Chaloupka et al. (2004:150). ��������������������23
x Synopsis of the Biological Data on the Leatherback Sea Turtle
List of Tables
Table 1. The size (curved carapace length, CCL—except Puerto Rico (Culebra) and French Guiana
(Ya:lima:po) presented as straight carapace length/width, SCL/SCW) of adult female leatherback sea
turtles at their nesting grounds. Table is not comprehensive; locations were selected for geographic
representation. � 7
Table 2. The mass of juvenile and adult (primarily gravid female) leatherback sea turtles. Gender (F, M)
not reported for juveniles (Juv). Table is not comprehensive; locations were selected for geographic
representation. � 8
Table 3. Reported average yolked egg diameters (mm) and egg masses (g) for leatherback sea turtles.
Number of clutches tallied appears in brackets, with number of eggs measured in parentheses. ± 1 SD
is noted. � 9
Table 4. Straight carapace length and width (mm), and body mass (g) of leatherback sea turtle
hatchlings. Data shown are means ± standard deviations (or ranges), with sample sizes (number of
hatchlings measured) in parentheses. An asterisk (*) indicates that hatchlings were 3-5 days old at the
time of measurement; (**) indicates total length. �10
Table 5. Leatherback sea turtle morphology from two specimens captured at sea. SCL (SCW) =
Straight carapace length (width); CCL (CCW) = Curved carapace length (width). �11
Table 6. Published records that define the known northern and southern geographic range for
successful egg-laying by leatherback sea turtles. �21
Table 7. Indirect estimates of age at maturity for leatherback sea turtles. �27
Table 8. Nesting behavior in leatherback sea turtles. Durations for stages (min) for the Atlantic
coast of Costa Rica were recorded during a single nesting at Matina in 1958 (Carr and Ogren 1959).
Mean durations in minutes (± 1 SD) for St. Croix, U.S. Virgin Islands represent a composite of 113
nestings at Sandy Point National Wildlife Refuge in 1985 (Eckert and Eckert 1985). Mean durations in
minutes (± 1 SE) for Playa Grande, Costa Rica, were collected over 11 nesting seasons (sample size in
parentheses). * denotes values given for crawling while both emerging from and returning to the sea. �29
Table 9. Clutch size (yolked eggs only) and average number of yolkless eggs per clutch for leatherback
sea turtles. Where available, sample size (number of clutches tallied) appears in parentheses and ± 1
SD is noted. �33
Table 10. Occurrence and duration of nesting seasons for leatherback sea turtles by geographic region. �36
Table 11. Internesting periods for leatherback sea turtles, defined as the number of days between
consecutive successful egg-laying events within a nesting season. Range of values and number of
intervals (n) are also given. �37
Table 12. Clutch frequency (number of clutches per season) in leatherback sea turtles. Observed Clutch
Frequency is the number of confirmed successful egg-laying events. Estimated Clutch Frequency is
calculated by dividing the number of days between the dates of the first and last observed nesting
by the internesting period (cf. Frazer and Richardson 1985). Total Clutch Frequency is an estimate
that attempts to take into account egg-laying events before and after the first and last observations,
respectively (cf. Rivalan). Sample size (=number of clutches, but see Santidrián Tomillo et al. 2009) in
parentheses; asterisk (*) indicates a range of mean annual values. �39
List of Tables xi
Table 13. Remigration intervals for leatherback sea turtles, defined as the number of years between
consecutive nesting seasons. In parentheses is the proportion (%) of the nesting cohort exhibiting the
remigration interval, or the number (n) of intervals examined. �40
Table 14. Descriptions of the anatomy of embryonic and hatchling leatherback sea turtles.
Source: Miller (1985). �41
Table 15. Post-ovipositional embryonic statges in leatherback sea turtles. Source: Deraniyagala (1939). �41
Table 16. Pre-ovipositional embryonic stages, defined as the intra-oviducal period and development
prior to the formation of 24 pairs of somites, in the leatherback sea turtles. Source: Miller (1985). �42
Table 17. Incubation duration and hatching success for leatherback sea turtles. Hatching success is
generally calculated as the number of hatched eggs (or hatchlings) divided by the number of eggs in
a clutch. Emergence success is calculated as the number of hatchlings that emerge from the nest to
the beach surface, divided by the number of eggs in a clutch. Nest location refers to whether clutches
developed in situ, in a hatchery, in Styrofoam® incubators, or were relocated to another location on the
beach. Data are shown as mean ± SD. Sample sizes (number of clutches) in parentheses; asterisk (*)
indicates a range of annual means. �44
Table 18. Predators of leatherback sea turtles. Taxonomic detail reflects that given in the source
reference. Life stage affected: E = egg; H = hatchling; J = juvenile; A = adult. �48
Table 19. Parasites and commensals of leatherback sea turtles. Taxonomic detail reflects that given in
the source reference. �56
Table 20. Prey items, targeted and incidental, of wild leatherback sea turtles, as determined by gut
content analysis or by direct observation. Taxonomic detail reflects that given in the source reference.
Life Stage (Stage): H = hatchling; J = juvenile; A = adult; [blank] = unknown or unreported.
Cnidarians are reported in early references as ‘coelenterates.’ �60
Table 21. Summary of reported metabolic rates (MR) for leatherback sea turtles. Activity levels:
Resting = fed (unless noted as fasted), quiescent turtles; Active = continuous non-maximal activity
(e.g., swimming, crawling); Max = sustained maximal metabolic rate; Field = at-sea field metabolic
rates (FMR, incl. all normal daily activity); Laying = during oviposition; Calculated = MR derived
from models based on activity, behavior and environmental factors. Mass values are mean ± SD, unless
otherwise noted. Source: adapted from Wallace and Jones (2008). �68
Table 22. Summary of leatherback sea turtle dive and movement parameters during post-nesting
migrations and while on putative foraging grounds. Max Duration = Maximum Duration; Max
Distance = Maximum Distance traveled during the tracking period. �74
Table 23. Summary of leatherback sea turtle movement parameters recorded during internesting
periods. Data shown are means ± SD, sample sizes in parentheses. Max Depth = Maximum Depth;
Max Duration = Maximum Duration; Total Distance = Total Distance traveled during the internesting
period. �77
Table 24. Diet, maximum longevity, and cause of death of leatherback sea turtles reared in captivity.
With the exception of the juvenile stranded in Puerto Rico, all specimens were obtained as eggs or
hatchlings. � 106
xii Synopsis of the Biological Data on the Leatherback Sea Turtle
The authors are very grateful to the following
colleagues, each of whom reviewed at least one
chapter of text and made important contributions to
the final draft: Larisa Avens, Ana Rebeca Barragán,
Rhema Kerr-Bjorkland, Paolo Casale, Claudia
Ceballos, Milani Chaloupka, Benoit de Thoisy, Peter
H. Dutton, Chan Eng-Heng, Allen M. Foley, Marc
Girondot, Matthew H. Godfrey, Brendan J. Godley,
Hedelvy J. Guada, Craig A. Harms, Graeme C.
Hays, George R. Hughes, Douglas Hykle, T. Todd
Jones, Irene Kinan Kelly, Jeff Kinch, Rebecca
L. Lewison, Suzanne R. Livingstone, Peter A.
Meylan, Jeffrey D. Miller, Richard D. Reina, Pilar
Santidrián-Tomillo, Christopher R. Sasso, George L.
Shillinger, Amanda L. Southwood, James R. Spotila,
Manjula Tiwari, and Anton (Tony) D. Tucker.
The authors are particularly indebted to Sandra L.
MacPherson (U.S. Fish and Wildlife Service) and Dr.
Kelly R. Stewart (NOAA National Marine Fisheries
Service) for their full and careful review of the
entire manuscript.
A first draft of this Synopsis was prepared by Peter
C.H. Pritchard for presentation at the Western
Atlantic Turtle Symposium (WATS II) in Mayagüez,
Puerto Rico (October 1987), but never published.
We would like to recognize colleagues who reviewed
and made important contributions to several earlier
versions of the Synopsis over the course of many
years: Sneed B. Collard, Jacques Fretey, Sally
R. Hopkins-Murphy, Michael C. James, John A.
Keinath, Robert Lockhart, Molly E. Lutcavage,
Peter L. Lutz, Nicholas Mrosovsky, John (Jack) A.
Musick, Larry Ogren, David W. Owens, Frank V.
Paladino, Henri A. Reichart, Anders G.J. Rhodin,
Ricardo Sagarminaga, A. Laura Sarti M., Barbara
A. Schroeder, Sally E. Solomon, Malcolm Stark,
Jeanette Wyneken, and Rainer Zangerl. In all,
more than 50 researchers have given of their time,
expertise, and sometimes unpublished data to
ensure that the Synopsis is as complete as possible.
Thank you all!
The Synopsis is current with peer-reviewed
literature published to early-2009, at which time
the draft went through two rounds of international
peer-review and was queued into the Biological
Technical Publication series of the United States
Fish and Wildlife Service. The Synopsis is a product
of U.S. Fish and Wildlife Service Purchase Order
No. 20181-0-0169, and U.S. Fish and Wildlife Service
Grant Agreement No. 401814G050.
Acknowledgments
Executive Summary 1
The leatherback sea turtle (Dermochelys coriacea;
leatherback) is the largest and most migratory
of the world’s turtles, with the most extensive
geographic range of any living reptile. Reliable
at-sea sightings extend from ~ 71° N to 47° S.
This highly specialized turtle is the only living
member of the family Dermochelyidae. It exhibits
reduced external keratinous structures: scales are
temporary, disappearing within the first few months
and leaving the entire body covered by smooth
black skin. Dorsal keels streamline a tapered form.
The size of reproductively active females varies
geographically (~ 140–160 cm curved carapace
length, ~ 250–500 kg); a record male weighed 916
kg. Clutch size also varies geographically (~ 60–100
viable eggs), incubation is typically 60 days (during
which time gender is heavily influenced by ambient
temperature), in situ hatch success generally ranges
from 45–65%, and hatchlings (~55–60 mm carapace
length) are primarily black with longitudinal white
stripes dorsally.
The species has a shallow genealogy and strong
population structure worldwide, supporting a
natal homing hypothesis. Gravid females arrive
seasonally at preferred nesting grounds in tropical
and subtropical latitudes, with the largest colonies
concentrated in the southern Caribbean region
and central West Africa. Non-breeding adults and
sub-adults journey into temperate and subarctic
zones seeking oceanic jellyfish and other soft-bodied
invertebrates. Long-distance movements are not
random in timing or location, with turtles potentially
possessing an innate awareness of profitable
foraging opportunities. The basis for high seas
orientation and navigation is poorly understood.
Little is known about the biology or distribution of
neonates or juveniles, with individuals smaller than
100 cm in carapace length appearing to be confined
to waters > 26°C. Distribution of both juveniles
and adults most likely reflects the distribution and
abundance of macroplanktonic prey. Age at maturity
is debated and not conclusively known, but recent
estimates (26–32 yr) are similar to that of some other
sea turtle genera.
Studies of metabolic rate demonstrate marked
differences between leatherbacks and other sea
turtles: the “marathon” strategy of leatherbacks is
characterized by relatively lower sustained active
metabolic rates. Metabolic rates during terrestrial
activities are well-studied compared with metabolic
rates associated with activity at sea. One diel
behavior pattern involves deep diving (> 1200 m).
The species faces two major thermoregulatory
challenges: maintaining a high core temperature in
cold waters of high latitudes and/or great depths,
and avoiding overheating in some waters and
latitudes, especially while on land during nesting.
Biophysical models demonstrate that leatherbacks
are able to thermoregulate in varied environments
by combining large body size with low metabolic
rates, blood flow adjustments (e.g., counter-current
heat exchangers in their flippers), and peripheral
insulation (6–7 cm); a suite of adaptations sometimes
referred to as ‘gigantothermy,’ distinct from strict
ectothermy and endothermy. The primary means
of physiological osmoregulation are the lachrymal
glands, which eliminate excess salt from the body.
The leatherback was re-classified in 2000 by the
International Union for the Conservation of Nature
(IUCN) Red List of Threatened Species as Critically
Endangered. It remains vulnerable to a wide range
of threats, including bycatch, ingestion of and
entanglement in marine debris, take of turtles and
eggs, and loss of nesting habitat to coastal processes
and beachfront development. There is no evidence
of significant current declines at the largest of the
Western Atlantic nesting grounds, but Eastern
Atlantic populations face serious threats and
Pacific populations have been decimated. Incidental
mortality in fisheries, implicated in the collapse
of the Eastern Pacific population, is a largely
unaddressed problem worldwide.
Although sea turtles were among the first marine
species to benefit from legal protection and
concerted conservation effort around the world,
management of contemporary threats often falls
short of what is necessary to prevent further
population declines and ensure the species’ survival
throughout its range. Successes include regional
agreements that emphasize unified management
approaches, national legislation that protects
large juveniles and breeding-age adults, and
community-based conservation efforts that offer
viable alternatives to unsustainable patterns of
exploitation. Future priorities should include
the identification of critical habitat and priority
conservation areas, including corridors that span
multiple national jurisdictions and the high seas,
the creation of marine management regimes at
ecologically relevant scales and the forging of new
governance patterns, reducing or eliminating causal
factors in population declines (e.g., over-exploitation,
bycatch), and improving management capacity at
all levels.
Executive Summary
2 Synopsis of the Biological Data on the Leatherback Sea Turtle
Nomenclature
Valid Name
Dermochelys (Blainville 1816)
Dermochelys coriacea (Vandelli 1761)
Synonymy
This species was first described by Vandelli in 1761
(Fretey and Bour 1980, King and Burke 1997) as
Testudo coriacea. In 1816, Blainville proposed the
genus Dermochelys but failed to name D. coriacea
as the type species (Smith and Smith 1980). This led
to some confusion about the correct scientific name
for the species but generally since the publication of
Boulenger (1889), Dermochelys coriacea has been
considered the correct name for the leatherback.
The leatherback is the only living member of the
family Dermochelyidae (Stewart and Johnson 2006).
The history of the familial name is complex (Baur
1889, Pritchard and Trebbau 1984). Sphargidae
(Gray 1825) is the oldest name, but when the type
genus Sphargis (Merrem 1820) was recognized by
Baur (1888) to be a junior synonym of Dermochelys
(Blainville 1816), Lydekker (1889) argued the family
should also be subordinated to Dermatochelyidae
Fritzinger 1843 (see also Smith and Taylor
1950). Lydekker claimed that due to Aristotle’s
original Greek spelling, Dermatochelys (not
Dermochelys) was justified, and, hence, the family
Dermatochelyidae would be preferred. In fact,
Dermatochelys Lesueur 1829 (not Wagler 1830, c.f.
Pritchard and Trebbau 1984) is a junior synonym to
Dermochelys Blainville 1816, and the family name
based on it has not been used frequently.
The first use of the accepted name Dermochelyidae
is commonly credited to Wieland (1902) [who in fact
used “Dermochelydidae”], although there are earlier
publications (e.g., Baur 1889 [Dermochelydidae],
1890, 1891, 1893; Wieland 1900). It is not uncommon
to find variant spellings, often from the (possibly
inadvertent) omission of the “y” e.g., Dermochelidae.
Another variant, Dermochelydidae, has also been
used over the past century (Baur 1889, Wermuth
and Mertens 1977). Smith and Smith (1980) give a
detailed and lucid discussion of the nomenclatural
points involving Dermochelyidae.
The following synonymy is according to Pritchard
and Trebbau (1984):
Testudo coriacea sive Mercurii Rondeletius,
1554, Libri Pisc. Mar., Lyon: 450. Type locality:
Mediterranean Sea.
Mercurii Testudo Gesner, 1558, Medici Tigurini
Hist. Animal, Zürich, 4: 1134.
Testudo coriacea Vandelli, 1761, Epistola de
Holothurio, et Testudine coriacea ad Celiberrimum
Carolum Linnaeum, Padua: 2. Type locality: “Maris
Tyrrheni oram in agro Laurentiano.”
Testudo coriacea Linnaeus, 1766, Syst. Nat., Ed. 12,
1: 350. Type locality: “Mari Mediterraneo, Adriatico
varius” erroneously restricted to Palermo, Sicily, by
Smith and Taylor (1950).
Testudo coriaceous Pennant, 1769, Brit. Zoology, Ed.
3, 3, Rept.: 7.
Testudo arcuata Catesby, 1771, Nat. Hist. Carolina,
Florida, Bahama Isl., 2: 40. Type locality: coasts of
Carolina and Florida, as restricted by Mertens and
Wermuth, 1955.
Testudini Coriacee Molina, 1782, Sagg. Sulla Stor.
Nat. Chili, Bologna, 4: 216 (illegitimate name).
Tortugas Coriaceas Molina, 1788, Comp. Hist. Geog.
Chile, Madrid, 1: 237 (illegitimate name).
Testudo Lyra Lacépède, 1788, Hist. Nat. Quad.
Ovip., 1: table “Synopsis.”
Testudo marina Wilhelm, 1794, Unterhalt.
Naturgesch. Amphib.: 133. Type locality: all oceans.
Testudo tuberculata Pennant in Schoepf, 1801,
Naturgesch. Schildkr.: 144. Type locality:
not designated.
Chelone coriacea Brongniart, 1805, Essai Classif.
Nat. Rept. 26.
Chelonia coriacea Schweigger, 1812, Königsberg.
Arch. Naturwiss. Math., 1: 290.
Chelonias lutaria Rafinesque, 1814, Spec.
Sci. Palermo: 666. Type locality: Sicily (fide
Lindholm 1929).
Dermochelys coriacea Blainville, 1816, Prodrom.
Syst. Règn. Anim.: 119.
Chapter 1: Identity
Chapter 1: Identity 3
Sphargis mercurialis Merrem, 1820, Tent. Syst.
Amphib.: 19. Type locality: “Mari Mediterraneo
et Oceano atlantico” (substitute name for Testudo
coriacea Vandelli, 1761).
Coriudo coriacea Fleming, 1822, Phil. Zool., 2: 271.
Chelonia Lyra Bory de St-Vincent, 1828, Résumé
d’Erpét. Hist. Nat. Rept.: 80 (substitute name for
Testudo coriacea Vandelli 1761).
Scytina coriacea Wagler, 1828, Isis, 21: coll. 861.
Sphargis tuberculata Gravenhorst, 1829, Delicae
Mus. Zool. Vratislav., 1: 9.
Dermochelis atlantica LeSueur in Cuvier, 1829,
Règn. Anim., Ed. 2, 2: 406 (nomen nudum).
Dermatochelys coriacea Wagler, 1830, Natürl. Syst.
Amphib.: 133.
Dermatochelys porcata Wagler, 1830, Natürl. Syst.
Amphib.: expl. to pl. 1 (substitute name for Testudo
coriacea Vandelli, 1761).
Sphargis coriacea Gray, 1831, Synops. Rept., pt. 1,
Tortoises, etc.: 51.
Chelyra coriacca Rafinesque, 1832, Atlantic Jour.
Friend Knowl., 1: 64 (typographical error).
Testudo coriacea marina Ranzani, 1834, Camilli
Ranzani de Testudo coriacea marina, Bologna: 148.
Dermatochelys atlantica Fitzinger, 1836 (1835),
Ann. Wien. Mus., 1: 128.
Testudo (Sphargis) coriacea Voigt, 1837, Lehrb.
Zool., Stuttgart, 4: 21.
Dermochelydis tuberculata Alessandrini, 1838,
Cenni Sulla Stor. Sulla Notom. Testuggine coriacea
marina, Bologna: 357.
Chelonia (Dermochelys) coriacea van der Hoeven,
1855, Handboek Dierkunde: 548.
Testudo midas Hartwig, 1861, Sea and its Living
Wonders, Ed. 2, London: 152.
Sphargis coriacea Var. Schlegelii Garman, 1884,
Bull. U.S. Nat. Mus., 25: 303. Type locality: “Tropical
Pacific and Indian Oceans” erroneously restricted
to Guaymas, Sonora, Mexico by Smith and Taylor
(1950).
Sphargis schlegelii Garman, 1884, Bull. U.S. Nat.
Mus., 25: 295. Type locality: “Pacific (Ocean).”
Dermatochelys schlegeli Garman, 1884, Bull. Essex
Inst., 16, 1–3: 6. Type locality: “Tropical Pacific and
Indian Oceans.”
Sphargis angusta Philippi, 1889, An. Univ. Santiago,
Chile, 104: 728. Type locality: “Tocopilla, Chile.”
Dermatochaelis coriacea Oliveira, 1896, Rept.
Amph. Penín Ibérica, Coimbra: 28.
Dermochelys schlegelii Stejneger, 1907, Bull. U.S.
Nat. Mus., 58: 485.
Dermatochelys angusta Quijada, 1916, Bol. Mus.
Nac. Chile, 9: 24.
Dermochelys coriacea coriacea Gruvel, 1926, Pêche
Marit. Algérie, 4: 45.
Dendrochelys (Sphargis) coriacea Pierantoni, 1934,
Comp. Zool. Torino: 867.
Dermochelys coriacea schlegeli Mertens and L.
Müller, in Rust, 1934, Blatt. Aquar.-u-Terr. Kunde,
45: 64.
Type Locality
Vandelli (1761) specified the origin of his specimen as
“…maris Tyrrheni oram in agro Laurentiano,…”
and Linnaeus (1766) indicated “…habitat in Mari
mediterraneo, Adriatico rarius.” Smith and Taylor
(1950) restricted the type locality to Palermo, Sicily,
without discussion. As Fretey and Bour (1980)
observed, the original Vandelli type locality includes
a slight element of ambiguity, since “Laurentiano”
may refer to the ancient town of Laurentum, 8 km
northeast of Lido di Ostia (near Tor Paterno), 13 km
southwest of Rome; or it may refer to the present
town of Lido di Lavinio, 7.5 km north of Anzio and
22 km southeast of Rome. The type locality should
therefore be simply “…coast of Italy (western
Mediterranean), on the Tyrrhenian Sea near Rome.”
Taxonomy
Affinities
– Suprageneric
Phylum Chordata
Subphylum Vertebrata
Superclass Tetrapoda
  Class Reptilia
Subclass Anapsida
Order Testudines
Suborder Cryptodira
Superfamily Dermochelyoidea
Family Dermochelyidae
– Generic
Genus Dermochelys is monotypic.
– Specific
4 Synopsis of the Biological Data on the Leatherback Sea Turtle
Diagnosis.—This is a highly specialized sea turtle
with reduced external keratinous structures: scales
are temporary, disappearing within the first few
months after hatching, when the entire body is
generally covered by smooth skin (although traces
of scales may remain on eyelids, neck and caudal
crest); claws are absent (with few exceptions
in embryos and newly hatched young); and the
rhamphothecae on the upper and lower beaks
are thin and feeble. A conspicuous recurved cusp,
delimitated both anteriorly and posteriorly by a
deep notch, is on the anterior of each upper jaw. The
lyre-shaped carapace has seven longitudinal ridges,
or keels (sometimes described as five longitudinal
ridges, with an additional ridge on each side marking
the bridge), two anterior paramedial projections and
one posterior medial projection. The plastron has six
(three pairs of) weak keels that are also longitudinal.
Stout horny papillae line the pharyngeal cavity, but
not the choanae.
Unique features in the skull include: unossified
epipterygoid; rudimentary descending process on
parietal; parasphenoid rudiment in basisphenoid;
lack of contact between squamosal-opisthotic,
prootic-parietal, pterygoid-parietal, and pterygoid-prootic;
no coronoid and a cartilaginous articular. A
mosaic of dermal ossicles develops during the first
year to cover the carapace. Of the usual dermal
elements in the carapace, only the nuchal bone is
present, leaving the relatively unexpanded ribs free.
Plastron bones are also greatly reduced in size,
forming a flimsy ring; and there are normally eight
instead of nine elements; the entoplastron is absent.
Both the ribs and the plastral bones are embedded
in the subdermal cartilaginous layer. Adults, at more
than 2 m in total length and often exceeding 500 kg,
are the largest Recent Testudines. The black dorsal
coloration with white spots is also diagnostic.
Taxonomic Status
In terms of contemporary species, this family
is monotypic, and this often results in confusion
between familial, generic, and specific characters,
especially because the extant form, Dermochelys
coriacea, is so extraordinary. So unusual are the
dermochelyids that Cope (1871) created a special
suborder, Athecae, specifically for them. Although
variant spellings have been used, e.g., “Athecata”
(Lydekker 1889: 223 “amended from Cope”) and
“Athecoidea” (Deraniyagala 1939), this taxon was in
use as late as 1952 by Carr. However, the concept of
the Athecae as the sister group to other turtles has
been rejected by more recent phylogenetic studies.
A variety of detailed comparative studies, including
specimens of D. coriacea, have concluded that
Dermochelyidae is most closely related to the
cheloniid sea turtles. These investigations have
involved the skeleton (Baur 1886, 1889; Dollo 1901;
Wieland 1902; Versluys 1913, 1914; Völker 1913;
Williams 1950; Romer 1956); cranium (Nick 1912;
Wegner 1959; Gaffney 1975, 1979); penis (Zug 1966);
blood proteins (Frair 1964, 1969, 1979, 1982; Chen
and Mao 1981) and sequence data (e.g., Shaffer et
al. 1997, Krenz et al. 2005, Near et al. 2005, Naro-
Maciel et al. 2008).
Because the family Dermochelyidae includes only
a single living species, D. coriacea, published
diagnoses of the family, genus, and species tend
to be very similar. However, several fossil genera
of dermochelyids have been described. It is also
tempting to define the family in terms of known
characteristics, particularly of the soft parts of the
living species, even though it is generally impossible
to confirm that these characteristics were also shown
by the extinct species which, for the most part, are
known only from fragmentary fossils.
This caveat should be kept in mind when
applying the diagnoses of the family and
species presented by Pritchard and Trebbau
(1984)—“DERMOCHELYIDAE: A family of
turtles characterized by: extreme reduction of the
bones of the carapace and plastron (with the neural
and peripheral bones of the carapace, and the
entoplastron in the plastron, lacking; the pleurals
reduced to endochondral ribs, separated by wide
fenestrae; and the plastral bones reduced to narrow
splints, forming a ring of bones surrounding a great
fontanelle); development of a neomorphic epithecal
shell layer consisting of a mosaic of thousands of
small polygonal bones; claws and shell scutes lacking
(scales only present in the first few weeks of life);
skull without nasal bones; no true rhamphothecae;
parasphenoid overlain by pterygoids; prefrontals in
contact dorsally, with descending processes that are
moderately separated; unridged tomial surfaces;
a generally neotenic and oil-saturated skeleton;
extensive areas of vascularized cartilage in the
vertebrae, limb girdles, and limb bones; very large
body size; and marine habitat.”
Until recently the earliest dermochelyids were dated
from the Eocene (Europe, Africa, North America:
Romer 1956, de Broin and Pironon 1980, Pritchard
and Trebbau 1984), but are now confirmed from the
Cretaceous (Japan: Hirayama and Chitoku 1996).
Subsequent evolution led to several distinct lineages,
all but one of which became extinct (Wood et al.
1996).
In the most recent review of fossil dermochelyids
(Wood et al. 1996), six genera are recognized:
Cosmochelys Andrews 1919—Eocene of Nigeria,
one species; Dermochelys Blainville 1816—Recent
cosmopolitan, one species; Egyptemys Wood,
Johnson-Gove, Gaffney and Maley 1996—Eocene
of northern Egypt and North America, two species;
Eosphargis Lydekker 1889—Eocene of Europe,
two species; Natemys Wood, Johnson-Gove, Gaffney
and Maley 1996—Oligocene of Peru, one species;
Psephophorus Von Meyer 1847—Eocene through
Pliocene of Europe, North Africa and North
America, eight species.
Chapter 1: Identity 5
Specimens of Cosmochelys and Pseudosphargis
[Koenen 1891—Oligocene of Germany] are mere
fragments, and there have been discussions
about their true identity (Wood 1973); indeed,
Pseudosphargis is no longer considered viable (Wood
et al. 1996). Likewise, much of the Psephophorus
material is fragmentary, and it is impossible to
be certain about some of the identifications here
also. Some fossil dermochelyids are so incomplete
that not only have they given rise to discussions
about specific and generic identity, but ordinal and
class identity have also been questioned, for some
specimens have been identified as crocodiles or fish
(Deraniyagala 1939, de Brion and Pironon 1980,
Pritchard and Trebbau 1984).
Comprehensive studies of dermochelyid fossils have
been done on Eosphargis; Nielsen (1959) made a
detailed study of good material of E. breineri from
the Eocene of Denmark. It is possible that detailed
study of the fossil material will result in conclusions
that some of the genera presently recognized are
synonymous with Dermochelys, the oldest generic
name in the family.
According to Dutton et al. (1999), (i) the leatherback
sea turtle (Dermochelys coriacea; leatherback) is
the product of an evolutionary trajectory originating
at least 100 million years ago, yet the intraspecific
phylogeny recorded in mitochondrial lineages
may trace back less than 900,000 years; (ii) the
gene genealogy and global distribution of mtDNA
haplotypes indicate that leatherbacks may have
radiated from a narrow refugium, possibly in the
Indo-Pacific, during the early Pleistocene glaciation;
and (iii) analysis of haplotype frequencies reveal
that nesting populations are strongly subdivided
both globally (FST = 0.415) and within ocean basins
(FST = 0.203–0.253), despite the leatherback’s
highly migratory nature (see Chapter 4, Population
structure, Phylogeography, below).
Subspecies
No subspecies are recognized at the present time.
Of the numerous specific names that have been
applied to leatherback turtles since 1554 (see
Synonymy, above), all of those published before
1884 may be considered to represent simply
replacement or substitute names rather than a
conviction by an author that he had identified a
new kind of leatherback turtle. However, Garman
(1884a, 1884b) recognized a supposed new variety of
the leatherback, that he named Sphargis coriacea
Var. Schlegelii, or Dermatochelys (or Sphargis)
schlegeli schlegeli, as a subspecific name, which
has been utilized for the leatherbacks of the Indian
and Pacific Oceans by many authors subsequently,
including Carr (1952), Mertens and Wermuth (1955),
Caldwell (1962), Hubbs and Roden (1964), Stebbins
(1966), and Pritchard (1967). Moreover, a number of
influential authorities preceding Carr (1952) gave
schlegeli full species ranking. These authorities
include Stejneger (1907), Stejneger and Barbour
(1917), van Denburgh (1922), Bogert and Oliver
(1945), and Ingle and Smith (1949).
None of these authors, from Garman (1884a) to
Pritchard (1967), had undertaken analyses of the
actual differences between leatherback turtles from
different oceans. Museum material was inadequate
for this task, and the places where leatherbacks
may be found in quantity in the wild had, for the
most part, not been discovered. Moreover, Garman’s
proposal of the new name schlegeli was confusing
and inconsistent on several counts, and would not be
considered acceptable if published today. The only
demonstrated aspect of geographic variation relates
to the smaller adult size of females from the Eastern
Pacific (see Chapter 4, Population structure, Size
composition, below). While this is of interest, it may
derive from some aspect of the environment rather
than from genetic differences, and this character
alone should not be used to justify subspecific
recognition of this population.
If further study should reveal taxonomically valid
characteristics in D. coriacea in the Eastern Pacific,
the name angusta should be used rather than
schlegelii, the former having an Eastern Pacific type
locality (Chile), while the type locality of Garman’s
name schlegelii, to the extent that it can be known,
is Burma (i.e., the Indian Ocean) based on Tickell’s
(1862) detailed description of an adult leatherback
that had been captured on 1 February 1862 near the
mouth of the Ye River in the Province of Tenasserim,
Burma.
Standard Common Names
Throughout the world, the leatherback sea turtle
is known by many local names. Recently published
examples include India, where doni tambelu is used
(doni means “wheel of a bullock cart”) (Tripathy
et al. 2006), and Papua New Guinea (Kinch 2006),
where hana, hum, kareon, and nangobu are
among the tribal language terms for the species.
As summarized by Pritchard and Trebbau (1984),
the following are common vernacular names for
Dermochelys coriacea in the Atlantic: leatherback,
leathery turtle (English); trunk turtle, trunkback
turtle, coffinback, caldong (English-Caribbean);
tinglada (Spanish); canal, cardon, siete filos, chalupa,
baula, laúd, tortuga sin concha (Spanish-Latin
America); machincuepo, garapachi (Spanish-Pacific
Mexico); tortuga llaüt (Spanish-Canary Islands);
tortue luth (French); cada-arou (Galibi Indians-
French Guiana); aitkanti [aitikanti], sixikanti
(Suriname); caouana (Marowijne Carib); and
tartaruga de couro, tartaruga coriacea (Portuguese-
Brazil, Azores, Africa). See also Deraniyagala
(1939), Hughes (1974a), Mittermeier et al. (1980),
Fretey (2001), and Shanker and Choudhury (2006),
among others.
Definition of Size Categories
Hatchling—from hatching to the first few weeks
of life, characterized by the presence of the
umbilical scar.
6 Synopsis of the Biological Data on the Leatherback Sea Turtle
Juvenile—umbilical scar absent, with a maximum
size of 100 cm curved carapace length (CCL);
rarely seen but believed to occur only in waters
warmer than 26°C.
Subadult—carapace length > 100 cm CCL to
the onset of sexual maturity at 120–140 cm CCL,
depending on the population; able to exploit their
full biogeographical range.
Adult—sexually mature (> 120–140 cm CCL for
gravid females, depending on the population); the
size at sexual maturity for males is assumed to be
similar to that of females.
Morphology
Description
Informative general descriptions of this species
are presented by Deraniyagala (1939), Carr (1952),
Loveridge and Williams (1957), Villiers (1958),
Pritchard (1971a, 1979a, 1980), Ernst and Barbour
(1972), and Pritchard and Trebbau (1984). More
recently, Wyneken (2001) described the internal
anatomy in detail.
The size (carapace length) of reproductively active
females varies geographically, with population
averages of ~ 150–160 cm CCL in the Atlantic
and Indian Oceans, and ~ 140–150 cm CCL in
the Eastern Pacific (Table 1). Comparable data
are not available for adult males. From the few
measurements recorded in the literature (e.g.,
Deraniyagala 1939, 1953; Lowe and Norris 1955;
Donoso-Barros 1966; Brongersma 1969, 1972;
Hartog and van Nierop 1984; Hughes 1974a;
Maigret 1980, 1983; James et al. 2007), there would
appear to be no obvious difference in average size
between the sexes (but see Morgan 1990).
Eckert et al. (1989b) were the first to document the
average weight of a nesting cohort at the breeding
grounds, and these and later data collected at
Western Atlantic sites indicate (nesting) population
averages of 327 to 392 kg. There are no comparable
data for other geographic regions, or for males
(Table 2). The record weight is that of an adult
male (916 kg: Morgan 1990), which was ensnared
in a fisherman’s net off the coast of Wales, U.K.
Calculated relationships between body weight and
carapace length are variously presented (Hirth 1982,
Boulon et al. 1996, Leslie et al. 1996, Georges and
Fossette 2006).
The average diameter of a normal-sized viable egg
(52–55 mm) varies among populations. Population
averages for egg mass also vary geographically,
reportedly from 71.8 g to 84.3 g, with the largest
eggs associated with Western Atlantic populations
and the smallest with Eastern Pacific populations
(Table 3). Noticeably undersized yolkless eggs are
normally laid together with viable eggs; the former
are highly variable in size and shape. Average
hatchling size (straight carapace length, SCL) and
mass varies geographically, typically from 55 to 65
mm and from 40 to 50 g, respectively (Table 4).
There have been few analyses of the inter-relationships
between different morphometric
parameters (Table 5). In nesting females there is
a strong positive relationship between width and
length of the carapace, when measured either along
the curve (Hughes 1974a) or straight-line length
(Fretey 1978). Benabib (1983) established this for
both measuring techniques on the same specimens.
Head width and carapace length are also positively
related (Hughes 1974a), but these relationships have
been described only with linear models and no effort
has been made to test for allometry or to test other
types of models.
In a recent analysis of 17 morphometric
measurements obtained from 49 leatherbacks,
Georges and Fossette (2006) used a stepwise
backward analysis to show that body mass could be
estimated with 93% of accuracy from the standard
curvilinear carapace length (SCCL) and body
circumference at half of SCCL.
In hatchlings, the interrelationships between
different parameters are less clear. Hughes
(1974a) concluded that there was no significant
relationship between either carapace width and
carapace length or head width and carapace length;
however, Benabib (1983) found a very significant
positive relationship between carapace width and
carapace length.
Analyses of morphometric parameters, especially
when comparing results that span several decades,
may be compromised by the lack of standardized
measurement techniques. Divergent values from
distinct studies may only reflect discrepancies in
equipment, technique or experience (Frazier 1998),
rather than biologically significant differences in
the sizes of animals. Likewise, important biological
differences may be masked by non-standard
measuring techniques that make results appear
artificially similar. Hughes (1971a) concluded that
the differences between measurements made
over the curve or in a straight line amount to 6%
of lengths and 32% of widths. Hughes (1974a) and
Tucker and Frazer (1991) provide equations for
converting from straight carapace length (or width)
to curved carapace length (or width).
A related point concerns the fact that measurements
not only vary from straight to curved, but the end
points are not always the same. Measurements
may be made along a keel ridge or between keels,
at the anteriormost projection of the carapace
(paramedial keels) or at the more posterior median
keel. To further complicate the situation, the caudal
projection is sometimes broken (Godfrey et al. 2001).
The challenge led some workers to present two or
three different measurements for either curved
or straight techniques (e.g., Brongersma 1972,
Eckert et al. 1982, Benabib 1983, Eckert and Eckert
Chapter 1: Identity 7
Table 1. The size (curved carapace length, CCL—except Puerto Rico (Culebra) and French Guiana
(Ya:lima:po) presented as straight carapace length/width, SCL/SCW) of adult female leatherback sea turtles
at their nesting grounds. Table is not comprehensive; locations were selected for geographic representation.
Location
CCL (cm) Mean
± SD (range)
Sample
Size (n)
CCW (cm) Mean
± SD (range)
Sample
Size (n) Reference
Western Atlantic
Brazil (Espírito Santo)
159.8 ± 10.5
range: 139-182 24 – – Thomé et al. (2007)
French Guiana (Ya:lima:po)
154.6 ± 8.98
127-252 SCL 1,328
87.3 ± 6.21
67-109 SCW 1,328 Girondot & Fretey (1996)
Suriname1
154.1 ± 6.7
155.6 ± 6.7
range: 128-184
1,840
629
113.2 ± 5.0
114.5 ± 4.9
range: 97-135
801
383 Hilterman & Goverse (2007)
Venezuela (Playa Cipara, Playa
Querepare) 151.8 ± 6.2 – 110.0 ± 4.4 – Rondón et al., unpubl. data
Trinidad (Matura Beach)
157.6
range: 139.7-210.0 104 – – Chu Cheong (1990)
Trinidad (Matura Beach)
154.47 ± 5.03
range: 115-196 17,884
112.91 ± 6.97
range: 94-150 17,901
Nature Seekers, unpubl. data
1992-07
Costa Rica (Gandoca)
153.2 ± 7.39
range: 135-198 2,751 112 ± 5.53 2,751 Chacón & Eckert (2007)
Costa Rica (Tortuguero)
156.2 ± 10.6
range: 124.0-180.3 35 – – Leslie et al. (1996)
USA (St. Croix, USVI)
2
152.2
range: 139.4-175.8 19 – – Eckert (1987)
USA (Culebra, Puerto Rico)
147.0 ± 5.55
134.2-160.5 SCL 65 – – Tucker & Frazer (1991)
USA (Culebra, Puerto Rico) – –
83.4 ± 3.4
76-92 SCW 24 Tucker (1988)
USA (Florida: Juno Beach)
151.8 ± 6.63
range: 125.0-173.5 174
109.2 ± 5.03
range: 94-129 174 Stewart et al. (2007)
Eastern Atlantic
Equatorial Guinea
(Bioko Island)
156.06 ± 14.87
range: 120-200 458 – – Formia et al. (2000)
Republic of Gabon
(Pongara Beach)
150 ± 6
range: 139-169 22 – – Deem et al. (2006)
Gabon (Gamba Complex)
150.4 ± 7.6
range: 130-172 819
108.3 ± 6.6
range: 126-144 819 Verhage et al. (2006)
Western Pacific
Australia 162 ± 6.8 11 – – Limpus (2006)
Papua New Guinea (Kamiali,
Huon Coast)
166.0 ± 7.8
range: 149.1-173.0 96
119.3 ± 7.15
110-156.5 (sic) 97 Pilcher (2006)
Papua New Guinea (multiple
sites)
169.5 ± 8.74
range: 155-186.1 34 – – Hamann et al. (2006a)
Eastern Pacific
Mexico (Michoacán, Guerrero,
Oaxaca)
143.8 ± 6.88
range: 120-168 6,466
102.8 ± 17.9
range: 1-121 1,098 Sarti M. et al. (2007)
Mexico (Jalisco)
144.5
range: 135-151 4 – –
Castellanos-Michel et al.
(2006)
Costa Rica (Playa Langosta)
144.9 ± 6.7
range: 125-158 304
104.5 ± 7.8
range: 90-116 304 Piedra et al. (2007)
Costa Rica (Playa Grande)
147 ± 0.48 (SE)
range: 133-165 152
105.1 ± 0.39 (SE)
range: 93.5-116.8 152 Price et al. (2004)
8 Synopsis of the Biological Data on the Leatherback Sea Turtle
Location
CCL (cm) Mean
± SD (range)
Sample
Size (n)
CCW (cm) Mean
± SD (range)
Sample
Size (n) Reference
Indian Ocean
South Africa (Tongaland)
161.1 ± 7.0
range: 133.5-178.0 122
115.6 ± 6.5
range: 101.5-127.0 120 Hughes (1974a)
Mozambique
157.5 ± 80.4
range: 145.5-175 15
113.3 ± 64.1
range: 100-125 15 Louro (2006)
Sri Lanka 151.9 – 109.7 – Kapurusinghe (2006)
India (Great Nicobar Island) 155.7 125 113.1 125 Andrews et al. (2006)
1 mean ± SD was reported by year for Suriname, so that this entry features statistics from the year with the smallest average size and the year with the largest
average size; range is reported for the years 2001-2005, combined
2 USVI = U.S. Virgin Islands
Table 1, continued
Table 2. The mass of juvenile and adult (primarily gravid female) leatherback sea turtles. Gender (F, M)
not reported for juveniles (Juv). Table is not comprehensive; locations were selected for geographic
representation.
Location
Mass (kg) Mean
± SD (range)
Sample
Size (n) Gender Reference
Western Atlantic
French Guiana (Ya:lima:po)
389.7 ± 61.9
range: 275.6-567.3 182 F (nesting) Georges & Fossette (2006)
Trinidad (Matura Beach)
327.75 ± 65.134
range: 143-498.5 250 F (nesting) S.A. Eckert, unpubl. data
Costa Rica (Tortuguero)
346.8 ± 55.4
range: 250-435 22 F (nesting) Leslie et al. (1996)
USA (St. Croix, USVI)
327.38 ± 45.05
range: 262-446 26 F (nesting)
Eckert et al. (1989b)
S.A. Eckert, unpubl. data
USA (St. Croix, USVI) 259-506 102 F (nesting) Boulon et al. (1996)
Canada
392.6
range: 191.9-640 23 F, M, Juv (bycatch) James et al. (2007)
Eastern Atlantic
UK (Wales) 916 1 M (bycatch) Morgan (1990)
Northern Europe
(Norway, Scotland, Ireland)
302.67 ± 85.28
range: 241-400 3 M (capture, stranding) Brongersma (1972)
Northern Europe
(Norway, Scotland, Ireland)
323.33 ± 89.047
range: 224-396 3 F (capture, stranding) Brongersma (1972)
Eastern Pacific
USA (California) 349 kg 1 M (capture) Lowe & Norris (1955)
Indian Ocean
Sri Lanka
301.6
448.0
11
F (nesting)
F (nesting) Deraniyagala (1939)
South Africa (Natal)
340.08 ± 205.28
range: 150-646 5 F (stranding) Hughes (1974a)
South Africa (Natal)
320
27.3
11
M (stranding)
Juv (stranding) Hughes (1974a)
Chapter 1: Identity 9
Table 3. Reported average yolked egg diameters (mm) and egg masses (g) for leatherback sea turtles.
Number of clutches tallied appears in brackets, with number of eggs measured in parentheses. ± 1 SD
is noted.
Nesting Site Egg Diameter (mm) Egg Mass (g) Reference
Western Atlantic
Suriname (Bigi Santi) 53.0 – van Buskirk & Crowder (1994)
Trinidad (Matura Beach) 55.0 (30) – Bacon (1970)
Trinidad (Matura Beach)
55.0 [12] (120)
range: 52.0-59.0 – Maharaj (2004)
Costa Rica (Matina)
55.4 [1] (66)
range: 50.3-59.0 – Carr & Ogren (1959)
Costa Rica (Playa Gandoca) 53.2 ± 0.93 (3,250) – Chacón & Eckert (2007)
Costa Rica (Tortuguero) 54.0 ± 1.4 (613) 84.3 ± 5.2 (613) Leslie et al. (1996)
USA (St. Croix, USVI) 54.1 (926) – Eckert et al. (1984)
USA (Humacao, Puerto Rico) 54.5 ± 1.8 [9] (90) – Matos (1986)
USA (Culebra Island, Puerto Rico)
53.1 ± 2.2 (500)
range: 45.7-58.8 – Tucker (1988)
USA (Brevard County)
51.0 [7] (70)
range: 47.0-57.0 – Maharaj (2004)
Eastern Atlantic
Bioko
55.0 (4)
range: 54-56 – Butynski (1996)
Eastern Pacific
Costa Rica (Playa Grande) – 80.9 ± 7.0 (6,638) Wallace et al. (2006a)
Costa Rica (Playa Grande) – 76.2 ± 6.6 (30) Bilinski et al. (2001)
Mexico (Mexiquillo, Michoacan)
53.2 ± 0.31 (3,766)
range: 34.8-63.6
79.95 ± 7.85 (3,825)
range: 57.2-121.6 L. Sarti M., in litt. 22 June 1991
Western Pacific
Malaysia (Terengganu) – 71.8 (50) Simkiss (1962)
Australia (Wreck Rock) 53.2 ± 1.1 (120) 82.0 ± 4.2 (70) Limpus et al. (1984)
Australia1 52.9 (435) – Limpus & McLachlan (1979)
Papua New Guinea
52.2 ± 2.3 [17] (340)
range: 46-58 – Hamann et al. (2006a)
Indian Ocean
South Africa (Tongaland)
53.1 ± 1.49 (165)
range: 50-56 [1] – Hughes (1974b)
Ceyon [Sri Lanka]
52.5 [3] (18)
range: 51-54 61-85 Deraniyagala (1939)
Sri Lanka 53.2 (34) 79.6 (33) Kapurusinghe (2006)
1 denotes that value displayed is an average of annual averages
10 Synopsis of the Biological Data on the Leatherback Sea Turtle
Table 4. Straight carapace length and width (mm), and body mass (g) of leatherback sea turtle hatchlings.
Data shown are means ± standard deviations (or ranges), with sample sizes (number of hatchlings
measured) in parentheses. An asterisk (*) indicates that hatchlings were 3-5 days old at the time of
measurement; (**) indicates total length.
Location
Carapace
Length (mm)
Carapace
Width (mm) Body Mass (g) Reference
Western Atlantic
French Guiana 65 (12) 50 (12) – Bacon (1970)
Suriname
58.3 (25)
range: 56-60
41.2 (25)
range: 39-44 – Pritchard (1969, 1971a)
Suriname (Matapica) 59.5 ± 2.0 (360) – 44.7 ± 3.5 (340) Hilterman & Goverse (2007)
Suriname (Babunsanti) 59.1 ± 2.0 (100) – – Hilterman & Goverse (2007)
Trinidad
67 (2)
range: 66-68
49.5 (2)
range: 49-50 – Bacon (1970)
Costa Rica 62.8 (30) 41.8 (30) – Carr & Ogren (1959)
Costa Rica (Tortuguero) – – 45.7 ± 0.9 (6) Thompson (1993)
Costa Rica (Gandoca)
59.6 ± 4.5 (2,621)
range: 54-61 –
46.6 ± 6.1 (2,621)
range: 39-52 Chacón & Eckert (2007)
USA (Hutchinson Island, Florida) – – 42.5 ± 3.0 (26) Wyneken & Salmon (1992)
*USA (St. Croix, USVI) – – 52.6 ± 0.2 (8) Lutcavage & Lutz (1986)
USA (Culebra, Puerto Rico)
**90.7 ± 4.2 (267)
range: 79.1-99.0
38.9 ± 3.5 (267)
range: 27.4-49.8
44.7 ± 4.2 (223)
31.5-55.0 Tucker (1988)
Western Pacific
Malaysia (Terengganu)
57.3 (200)
range: 51.0-64.8 –
38.2 (200)
range: 28.5-45.6 Chan & Liew (1989)
Australia (Queensland) 56.4-60.5 (20) – 41.2-53.5 (20) Limpus & McLachlan (1979)
Australia (New South Wales)
61.0 (39)
range: 57.3-65.3 – – Limpus (2006)
Eastern Pacific
Mexico (Mexiquillo, Michoacan)
56.4±0.18 (2,800)
range: 50.5-62.8 –
41.2 ± 3.1 (2,937)
range: 32.4-50 L. Sarti M., in litt. 22 June 1991
Costa Rica (Playa Grande)
56.9 ± 2.1
(218 clutches)
38.8 ± 1.8
(218 clutches)
40.1 ± 2.7
(218 clutches) Wallace et al. (2006a, 2007)
Costa Rica (Playa Grande) – – 40.5 ± 1.0 (8) Jones et al. (2007)
Indian Ocean
Sri Lanka 53.5 (55) 32.7 (55) – Kapurusinghe (2006)
Ceylon [Sri Lanka] – – range: 32.6-33.6 Deraniyagala (1952)
South Africa (Tongaland)
58.7 (131)
range: 54.8-63.4
39.3 (124)
range: 36.3-43.5
37.3 (47)
range: 27.5-41.0 Hughes (1974a)
Chapter 1: Identity 11
Table 5. Leatherback sea turtle morphology from two specimens captured at sea. SCL (SCW) = Straight
carapace length (width); CCL (CCW) = Curved carapace length (width).
Location
Specimen Size
(Gender) Part or Organ
Dimension
or Mass Notes Reference
Western Atlantic
USA (Louisiana) Width: 95 cm (♀) Body 154 cm Length (max) Dunlap (1955)
Front Flipper 205 cm Tip-to-tip (span)
Hind Flipper 117 cm “Spread”
Heart 800 g
Alimentary Tract 1,620 cm Mouth-to-anus
Esophagus (alone)
183 cm
4,700 g
Diameter: 15 cm at origin,
7.6 cm “further down”
Stomach 203 cm
“Tubular and irregularly
dilatated at intervals of
7-12 cm”
Liver 8,000 g
Kidney
(R) 950 g
(L) 870 g
Ovary –
Each ovary had several
hundred immature yellow
eggs ≤ 6 mm
Eastern Pacific
USA (California)
144 cm SCL
97 cm SCW (♂) Body 63 cm Depth (max) Lowe & Norris (1995)
Head 24.5, 23.7 cm Length, width
Front Flipper
84.3, 29.8 cm;
235 cm
Length, width;
Tip-to-tip (span)
Hind Flipper 42.8, 26.8 cm Length, width
Tail 17.2, 5.7 cm Length, width
Penis 49.3, 9.6 cm Length, width
12 Synopsis of the Biological Data on the Leatherback Sea Turtle
1983) before handbooks aimed at global (Pritchard
et al. 1983, Eckert et al. 1999) and regional (e.g.,
Demetropoulos and Hadjichristophorou 1995,
Chacón et al. 2001, Shanker et al. 2003, Eckert and
Beggs 2006) audiences articulated standardized
protocols intended to encourage comparable
data collection between different populations and
different studies.
External Morphology and Coloration
Dermochelys coriacea has a leathery skin instead
of the usual outer covering of horny, keratinous
scales (Appendix A). It would be an overstatement,
however, to contend that there is an absence of all
cornified external structures.
In addition to a stratum corneum, a horny beak
is present but relatively weak. Claws may occur
in embryos or hatchlings, but they are unknown
in animals more than a few weeks old; on some
occasions, as much as 30% of a clutch may bear
claws. In addition, shallow temporary pits develop
on the enlarged scales at the distal ends of the first
two digits, and when a claw is present it protrudes
from such a pit. The “beady” scales of terminal
embryos and hatchlings are modified by ecdysis
and ontogenetic changes; after the first few months
scales are thin and inconspicuous. However, vestiges
of scale divisions are often seen on the eyelids,
neck and caudal crest of adults. These features
have been described in detail in numerous works of
Deraniyagala (1930, 1932, 1936b, 1939, 1953). These
exceptions to the oft-repeated generalization of
“no external keratin” (Carr 1952; Pritchard 1971a,
1979a, 1980; Ernst and Barbour 1972; Pritchard and
Trebbau 1984) are not just trivial points, but reflect
on ontogenetic and evolutionary considerations.
Clearly, the lack of scales and claws on the shell and
appendages of juveniles and older animals is not
a neotenic (paedomorphic) reduction, but a highly
specialized loss of a character virtually ubiquitous in
Testudines (Frazier 1987).
Often over 2 m in total length, the great size of this
turtle frequently gives the illusion that the body is
flattened, but the anterior of the animal is almost
barrel-shaped. Deraniyagala (1939) described the
plastron as “boat shaped anteriorly” and “apt to be
concave posteriorly.” A nucho-scapular hump has
been consistently described as the highest point
of the carapace in both hatchlings and adults; it is
supported by the columnar scapulae. Conspicuous
on the lyre-shaped carapace are seven longitudinal
keels that are irregularly serrate. Comments that
there are only five keels on the carapace result from
confusion; a narrow line of osteoderms (“platelets”)
may lie immediately dorsal to each marginal keel,
sometimes reducing the conspicuousness of this
outermost keel of the carapace (Brongersma 1969).
A pair of paramedial projections, conforming with
the paramedial (or costal) keels, extend the anterior
of the carapace, and an attenuated caudal projection
carries the medial and paramedial keels posteriorly.
The caudal projection commonly shows a variety
of injuries and abnormalities (Brongersma 1969,
Fretey 1982) which, based on studies in Tortuguero,
Costa Rica (Reyes and Troëng 2001, Harrison and
Troëng 2002), shorten the curved carapace length by
an average of 4.75 cm (Stewart et al. 2007).
The marginal keel, below the supramarginal, forms
the boundary between the carapace and plastron.
The latter has six (three pairs) of feeble longitudinal
keels, with the “medial” keel being composed of
two close-set ridges separated by a medial groove
(Deraniyagala 1930, 1939; Burne 1905; Brongersma
1969, 1970). Versluys (1913) described a “partly
paired” median row, as the anterior section is
sometimes fused. The anterior ends of the keels,
particularly on the plastron, are frequently without
sharp protuberances.
The front flippers are long and wide, both in relative
and absolute terms. A patagium, or cruro-caudal
fold, links the two hind limbs and the tail. The wide,
paddle-like hind limbs are posteriorly directed. A
“dorsal cutaneous ridge” or “crest” tops the laterally
compressed tail, and in both sexes the cloaca
is remarkably distant from the posterior of the
plastron (Deraniyagala 1939). The tail of the adult
male is longer and the cloaca extends further beyond
the posterior tip of the carapace (James 2004, James
et al. 2007).
No less remarkable is the head with a pair of large
posteriorly-pointed cusps, each bordered anteriorly
by a deep medial cleft and posteriorly by a deep
notch in the anterior of the upper jaw. Brongersma
(1970) and Rainey (1981) showed that in hatchlings
the cusps terminate in a sharp spine. The anterior
of the lower jaw has an equally conspicuous medial
cusp, and the sharp recurved point fits neatly into a
pit anterior to the choanae. A distinct internal ridge
runs parallel to each maxillary margin forming a
slot that receives each mandibular edge of the lower
beak when the mouth is closed (Deraniyagala 1932,
1939; illustrated by Brongersma 1970). The large
head and neck, which grade gradually into the body,
are nearly immobile. The eyelid slits are nearly
vertical. The nares open almost dorsally. There is no
external tympanum.
The outer layer of the body has been described as
“…tough, leathery and slightly flexible, composed
of rather loose fibrous tissue and containing no
cartilage…” (Dunlap 1955). Composed of connective
tissue, the “dermal carapace” is as thick as 36 mm
and makes up the bulk of the corselet; it is covered
by a cuticle with osteoderms which together are only
5 mm thick (Deraniyagala 1932, 1936b, 1939, 1953).
External pores pierce the anterior of the carapace
between the supramarginal and inframarginal
keels, and from 15–33 mm posterior to the edge
of the corselet. They occur in hatchlings as well
as in adults, and as many as three or four pores
may be seen on each side. In the young turtle,
each pore is surrounded by four or five scales, but
the adult has only four or five lines radiating out
from each opening (Deraniyagala 1932, 1936, 1939;
Chapter 1: Identity 13
Brongersma 1970). The pores are probably related
to Rathke’s gland (Rainey 1981).
Coloration.—Adults are matte, or slate, black on
the carapace, with interrupted white lines on the
keels; white spots, often in three or four longitudinal
lines, are between keels. The head has large white
blotches, some of which may extend to the jaws;
five longitudinal rows of spots may be discernible
on the dorsal neck surface. The bases of the flippers
have many white spots, and the top of the tail crest
is white. White dominates much of the ventral
surface, particularly along the keels. A black band
may extend from the inguinal area to the cloaca. For
details of coloration see Deraniyagala (1930, 1932,
1936, 1939) and Pritchard and Trebbau (1984).
There is tremendous variation in the coloration
of individuals within populations, as evidenced
by diversity among gravid females on the same
nesting beach. White or pale spotting may vary
from faint to abundant, so that females may range
in coloration from nearly all black to boldly spotted.
Some investigators contend that individuals may
be recognized by differences in white (Duguy et al.
1980) or pink (McDonald and Dutton 1996) markings
on the head. Descriptions of animals that are brown
with yellowish markings (Duméril and Bibron
1835, Yañez 1951) are evidently based on mounted
specimens where the oil has migrated to the exterior
of the body. The appearance of an animal depends on
its status; colors will be less intense if it is dry and
dusty, more intense if wet.
Adult leatherbacks have a pink spot on the top of
the head. In females, this mark has been thought to
be a scar or abrasion produced by the male during
copulation (Pritchard 1969, Hughes 1974a, Lazell
1976), but Benabib (1983), in the first quantitative
study, argued that since the pink crown is constant
and there is no evidence of lesions associated with
it, this mark is more likely a normal part of the
adult coloration. The pink spot is now known to be
associated (in both sexes) with the pineal gland.
According to Wyneken (2001), “…the ductless
pineal gland (epiphysis) is a dorsal extension of the
brain; it connects indirectly to the dorsal surface
of the braincase, it is located deep to the fronto-parietal
scale in cheloniids and the ‘pink spot’ in
Dermochelys [and is] responsible for modulating
biological rhythms.” McDonald et al. (1996) have
used the mark to identify adult individuals.
Hatchlings are intense black dorsally, or “blue
black” according to Deraniyagala (1939), with white
longitudinal keels, except the anterior of the medial
keel, which is interrupted with black. The three
inner lines extend dorsally onto the neck, where
two more lines occur between them. The margins
of the flippers, except at the distal ends of the first
and second digits, are white. Ventrally, the plastron
keels are covered by broad white longitudinal bands
with black in between. The throat and bases of
the flippers are mainly white (for developmental
descriptions, see Chapter 3, Embryonic and
hatchling phase, below).
Little is known of the coloration of young
juveniles. During their first year the carapace is
totally dark, but thereafter intense white spots
develop; in contrast, the plastron is mostly white
with longitudinal black markings paralleling the
umbilicus on each side (Deraniyagala 1936b, 1939;
Brongersma 1970; Hughes 1974a; Pritchard and
Trebbau 1984).
Eggs.—Cross-sections of decalcified and stained
egg shell indicate that the shell membranes are
about 250 μm thick and that the matrix of the shell
is only about half that thickness. There is said to be
no change in structure during incubation, and no
indication that the membranes detach from the outer
shell (Simkiss 1962).
The ultrastructure of Dermochelys egg shell was
investigated by Solomon and Watt (1985), who
presented numerous scanning electron micrographs.
Mainly, the exterior of the shell is composed of
the spicular aragonite form of calcium carbonate;
these crystals are laid down in radial patterns
indicating the presence of saucer-shaped nucleation
sites of membrane fibers in the mammillary layer
(Solomon and Reid 1983). A secondary crystal
layer shows a great variety of crystalline forms;
interspersed randomly among the aragonite crystals
are, in particular, calcite blocks and flattened
lozenge-shaped crystals. These may occur singly
or stacked with secondary crystal growths. Pores
were not observed, but the shell is thin enough that
gaseous exchange occurs across it. No outer cuticle
was observed.
Infrared spectrophotometry showed a dominant
absorption peak at 860 cm (corresponding to
aragonite) and another clear peak at 879 cm (calcite),
indicating that calcite comprises only about 5% of
the crystal. The mechanism for production of even
this small proportion of calcite is not understood, but
indicates changes in the oviductal environment (e.g.,
pH, ionic content, temperature, trace elements). It
was hypothesized that phosphorus, which is absent
from the secondary crystalline layer, is intimately
involved in the production of aragonite (Solomon and
Watt 1985).
Internal Morphology
The only cryptodires known to lack flaps or ridges
around the lateral margins of the choanae are
Dermochelys and the Cheloniidae. In Dermochelys,
the choanae are remarkably large and anteriorly
placed (Parsons 1968), with no surrounding papillae
(Deraniyagala 1939, Parsons 1968, Brongersma
1970). Villiers (1958) referred to unicellular nasal
glands. The function of these is unclear, and further
anatomical details were not presented. Detailed
descriptions of the chondrocranium, nerves and
sinuses of the head were given by Nick (1912). The
cranial arteries were investigated by Albrecht (1976).
14 Synopsis of the Biological Data on the Leatherback Sea Turtle
Alimentary System.—The anatomy of the
alimentary system has been described by Rathke
(1846 in Burne 1905), Vaillant (1896), Burne (1905),
Dunlap (1955), Rainey (1981), and Hartog and van
Nierop (1984). From the pharyngeal cavity to the
cardiac sphincter, sharp papillae with horny sheaths
line the esophagus, pointing posteriorly, and forming
practically all the exposed inner surface (see Dunlap
1955, Villiers 1958). They occur in embryos as well
as in adults, decreasing in length and thickness of
keratinous armor from the pharynx (8 cm long in
adults) to the stomach (where they are soft and only
a few mm long). Burne (1905) reported that these
papillae are always single at the anterior end of the
esophagus, often bifid in the middle, and sometimes
trifid at the posterior, or cardiac, end.
There is no possibility of pharyngeal-esophageal gas
exchange, for the thick keratinous sheaths provide
poor surfaces for efficient gas exchange and the
papillae are very poorly vascularized (Brongersma
1970; see also anatomical descriptions in Dunlap
1955 and Hartog and van Nierop 1984). Instead,
the papillae are thought to function in retaining
food (Bleakney 1965, Brongersma 1970, Hartog
and van Nierop 1984). Versluys (1913) argued that
a close relationship between Dermochelys and the
cheloniids is evidenced by the fact that only these
turtles have highly developed esophageal papillae.
The anterior part of the alimentary canal seems
to be highly variable, or else there has been some
confusion in distinguishing different parts. The main
constant in descriptions of the esophagus is its horny
papillae. Burne (1905) described and illustrated a
looped esophagus with the ascending limb rising,
nearly parallel to the descending limb, to meet the
stomach; all of this was contained within a peritoneal
sac. He concluded that the unusually long and
bent esophagus and the complicated stomach were
somehow related to the well developed mesenteric
sac. Dunlap (1955) agreed that the trachea and
esophagus are “uncommonly long” (11% of the
total length of the alimentary canal), and this was
thought to simply accommodate the extension of the
neck. The esophagus was said to make a “fish-hook
curve” but neither a tight loop nor a mesenteric sac
were mentioned.
Villiers (1958) and Bleakney (1965) agreed with
the description in Burne (1905), referring to the
esophagus as recurved or “J-shaped.” Rainey
(1981), however, clearly showed a hatchling with an
esophagus that completely encircled the anterior
stomach, and he stated that the mesenteries
supporting the esophagus and stomach are more
complex than in the cheloniids. Hartog and van
Nierop (1984) added further support to the concept
of a relatively long esophagus. They pointed out that
its length is not strongly correlated to body size,
suggesting that there is great individual variation
and/or that the presence or absence of food has a
marked effect on gut length and form. Again, there
was no mention of either a tight loop or a mesenteric
sac in the esophagus. Pritchard and Trebbau (1984)
stated that the esophagus is singularly long and
looped, and they suggested that it serves as a food
storage organ.
Variation in the anatomy of the stomach is
apparently even greater. Vaillant (1896) described
the stomach to be proportionally longer than in
cheloniids and more complex, with a globular
sac followed by a tubular section. The latter was
U-shaped, twice as long as the former and divided
internally by folds, some of which were virtually
diaphragms with central perforations. A fibrous
fascia enveloped the stomach. Burne (1905)
described and illustrated an anterior globular
part and a posterior U-shaped tubular part. The
tubular stomach was illustrated as tightly looped
with two limbs descending and one ascending; it
had approximately 13 compartments formed by
approximately 13 irregular transverse folds, but no
diaphragms perforated in their centers. The globular
stomach was enclosed within, and the tubular
stomach was included within, a peritoneal sac.
Dunlap (1955) reported only that the gastrointestinal
lining made an abrupt transition at the cardiac
sphincter from the papillae to the glandular mucosa,
and that the stomach was irregularly dilated.
Rainey (1981) stated that the stomach was composed
of two distant parts, clearly showing loops in the
posterior tubular stomach. Hartog and van Nierop
(1984) described the stomach as unusually long and
made up of a sac-like anterior part and a larger
tubular posterior part. They reported that it is the
anterior stomach that is U-shaped and muscular,
and both legs of the U are tightly connected by
mesentery and connective tissue. The tubular
stomach is thin and subdivided into compartments
by 16 distinct, permanent, transverse folds, each
provided with a sphincter muscle. Although there
was great variation in the development of these
compartments, both within and between stomachs,
consistently there were two small but well isolated
compartments just anterior to the pylorus. A rich
plexus of large vessels was observed between the
bends of the tubular stomach (Vaillant 1896). Only
a left anterior abdominal vein has been observed
(Rathke 1848 in Burne 1905, Burne 1905).
According to Vaillant (1896), there is no caecum, but
large and small intestines are easily distinguished
by external diameter. The wall of the small intestine
is very thin and covered with a honeycomb-like
mucosa, more complicated than in any other
Testudine. A gall bladder duct enters the small
intestine in the transverse limb at two places, but
the connection is functional only at the site more
distant from the gall bladder (as much as 9 cm away)
where a slit-like opening is bordered by foliate
lips (Burne 1905). What may be “…an extremely
vestigeal Meckel’s diverticulum…” was observed in
the free ventral mesentary some 40 cm posterior of
its beginning (Burne 1905).
Chapter 1: Identity 15
The liver consists of two broad lobes of equal
length, but the right lobe is larger; the two lobes are
connected by two narrow bands (Deraniyagala 1930,
1939).
Little is documented about the cloaca. Deraniyagala
(1939, 1953) described a young specimen that
expelled 20 cc of water, and he considered this
as proof that mucosal respiration occurs in the
cloaca. However, with a lack of supportive evidence
it is difficult to accept that this could contribute
significantly to metabolic needs. As Hartog and
van Nierop (1984) pointed out, there is no strong
relationship between gut length and body size.
However, the relative lengths of various parts of the
gut do not differ greatly between individuals.
Respiratory System.—Paired lateral folds in the
larynx appeared to be “rudimentary vocal cords”
(Dunlap 1955). The larynx is notable in that the
procricoid cartilage forms a process on the anterior
dorsal surface of the crico-thyroid, instead of being
completely separate. The first complete tracheal ring
is the seventh (Burne 1905); further information is
in Rathke (1846 in Burne 1905). Around the margins
of the trabeculae and extending into the air spaces
were bundles of smooth muscle; these would provide
the mechanism for active expiration from the depths
of the lungs. The alveolae are lined with a rich plexus
of thin-walled capillaries, evidently not covered by
an alveolar epithelium (Dunlap 1955).
Circulatory System.—The heart was observed to
be unusually long and narrow for a Chelonian, due
mainly to the ventricle forming a long and stout
gubernaculum cordis; this posterior half of the
ventricle is virtually solid muscle, without a cavity.
The auricular walls are relatively thin (Burne 1905).
The anterior of the ventricle has been described as
“spongy” having many muscular trabeculae; as the
coronary artery is relatively small and the coronary
vein is large, it was suggested that a major part of
the blood supply comes directly from the ventricle
chamber (Dunlap 1955).
The left aorta, notably on the dorsal wall, has a
linear row of small outpouchings that pass into the
interaortic septum. Also unique to this turtle is
the course of the left aorta. It leaves the ventricle
on the right side of the muscular “septum” and at
the top of the truncus, goes past the opening of the
right aorta, and joins the brachiocephalic trunk.
The communication between the left aorta and the
brachiocephalic trunk is comparable to the Foramen
of Panizza in the Crocodylia (Adams 1962), but since
these features are based on one specimen, it is not
known how constant they are in Dermochelys.
The pulmonary artery originates in a special
subchamber of the ventricle, and although this
shows a tendency toward an advanced four-chambered
heart, the separation was thought not
to be homologous to the intraventricular septum
of crocodiles, birds, and mammals. Shortly after
their bifurcation, the pulmonary arteries have
distinct muscular thickenings that were thought
to be sphincters (Koch 1934, Dunlap 1955). Dunlap
postulated that the sphincters close and the heart
rate drops as part of an automatic response to
diving, which is perhaps stimulated by the extension
of the neck.
Evidently unaware of these earlier brief
descriptions, Sapsford (1978) described and
illustrated the results of dissections of the
pulmonary artery. Just distal to the ductus Botalli
there is an abrupt thickening of the walls of the
pulmonary artery, from 1.5 to 3.9 mm in an adult
specimen. At the same time, the external diameter
decreases by a factor of 0.5. The thickened wall
has a remarkable concentration of smooth muscle,
which after an unspecified distance, but evidently
several cm, ends abruptly. It was originally thought
that this sphincter served to shunt blood away
from the lungs during diving/apnea to reduce
oxygen consumption in non-vital areas. However,
the presence of sphincters in land tortoises raised
the possibility that there is another function, the
control of heat exchange (loss especially) via the
peripherally situated lungs. It was reasoned that
the primary function of the pulmonary artery
sphincter is thermoregulatory, and that this
system was elaborated on as a diving adaptation
secondarily as ancestral Testudines adapted to the
marine environment.
A countercurrent heat exchanger has been described
from the limb bases; it consists of well defined
vascular bundles of closely packed vessels with as
many as four major veins per artery (Greer et al.
1973). It occurs in hatchlings as well as in adults
(Mrosovsky 1980) and has been linked to an ability
to “thermoregulate” specifically in heat conservation
(see Chapter 3, Nutrition and metabolism,
Thermoregulation, below). There is also a
suggestion that a counter-current heat exchanger
exists in the region of the nares “to conserve body
heat” (Sapsford and Hughes 1978).
Urogenital System.—The urogenital system has
been briefly described by Burne (1905) and Dunlap
(1955). Microscopic examination of peripheral
portions of the adult kidney revealed what appeared
to be nephrogenic tissue in subcapsular islands.
Hence, nephrons are thought to be produced
throughout life (not only until hatching), which
would enable an increase in excretory function
during growth. An ability to increase excretory
function is of great importance since body mass
increases by a factor of 104 (Dunlap 1955).
The ureters arise from the medial aspect near the
caudal end of each kidney and continue caudally to
enter the cloaca by separate lateral openings in close
association with the ends of the oviducts. The ureters
do not communicate directly wtith the urinary
bladder, but open freely into the cloaca (where the
urine is refluxed into the urinary bladder). Chemical
16 Synopsis of the Biological Data on the Leatherback Sea Turtle
analysis of urine (from postmortem specimens)
showed urea nitrogen = 140 mg dL–1, uric acid = 320
mg dL–1, and chloride = 503 mg dL–1 (Dunlap 1955).
The posterior end of a structure thought to be the
“interrenal organ” was examined histologically:
oval bodies, always associated with hyalinized
scars, were thought to be primordial follicles, and
it was suggested that this organ may be the true
source of ova, while the anatomical “ovary” is only
a repository for developing eggs (Dunlap 1955). In
immature females the oviducts do not communicate
with the cloaca, but they are imperforate, separated
by a “hymen” (Burne 1905, Dunlap 1955).
The penis is relatively simple; the glans consists of
only a single U-shaped fold, apparently an enlarged
continuation of the seminal ridges. Terminating
on the inner surface of the fold is the single
seminal groove; sinuses are evidently absent. This
condition is comparable to that in the other Recent
sea turtles and less elaborate than that found in
other cryptodires; it led to the conclusion that
Dermochelys is closely related to the other extant
sea turtles (Zug 1966).
Muscular System.—Detailed general descriptions
of the muscular anatomy are given by Rathke
(1846), Fürbringer (1874) and Burne (1905).
Poglayen-Neuwall (1953) did detailed studies of
jaw musculature and innervation in a Dermochelys
young enough to have scales; these findings were
then compared with those from other species. Burne
(1905) presented several notable observations that
distinguish D. coriacea from other chelonians.
These include: the cervico-capitis takes its origin
only from vertebrae IV and V and not from III; the
transversalis cervicis inserts onto the basioccipital,
as well as onto vertebrae I and II; the sphincter
colli inserts onto the scapula; the longus colli has no
origin from anterior ribs or the nuchal “plate”; the
humero-carpali-metacarpalis I inserts onto the head
of metacarpal I, not upon the radius and carpus.
The musculature of the thoracic and lumbar regions
is in a degenerate condition, and Burne (1905) was
unable to distinguish separate muscle masses.
However, muscles extend posteriorly beyond
the 9th rib, and he concluded that the degree of
degeneration is less than in other chelonians and,
thus, that the unique carapace of D. coriacea is
primitive and not a retrograde specialization. The
anterior half of the body cavity is almost all pectoral
musculature. Several fibromuscular sheets divide
the abdominal cavity into compartments. One sheet
originated from the ventral surface of the lung and
inserted into the capsule of the right lobe of the
liver; it was thought to function as a diaphragm
(Dunlap 1955).
Conspicuous fat bodies are present in Dermochelys.
The green fat of this species occasionally resembles
multilocular brown fat, but there is considerable
variation in fat color and no knowledge of the
primary function of fat bodies. The thickness of
“the fat layer” at the juncture of the carapace
and plastron, of an adult-sized female caught in
Cornwall, England, was 45–55 mm (Brongersma
1972). The hatchling has discrete lenticular, yellow-white
fat bodies in both axillary and inguinal regions,
which are (relatively) larger than in cheloniids
(Rainey 1981).
The high concentration of oil in Dermochelys tissues
is remarkable; the oil is pervasive even in the
skeleton and outer body covering.
Cranial Morphology
Skull.—The most important studies of the skull are
those of Nick (1912) and Wegner (1959), as well as
Gaffney (1979) who presented eight illustrations
and listed another nine publications in which there
are valuable illustrations (see also Deraniyagala
1939, 1953). Because it is so unusual, the skull of this
species is one of the best studied and illustrated of
all the turtles (Gaffney 1979). In comparison with
most turtles, many cranial elements are reduced
or neotenic, and despite its large size, the bones
are of low density and poorly fused; hence, the
skull is weak and easily disarticulates post mortem.
Its general form is unique. There is no significant
temporal emargination, and the supraoccipital
process is almost totally occluded dorsally by
the skull roof. Deep notches in the midline of the
maxillaries as well as the anterior cutting surface of
each maxilla produce a conspicuous cusp on either
side of the jaw; both the premaxillary and maxillary
contribute to the cusp (Appendix B).
Gaffney (1979) discussed the characteristic features
of D. coriacea, of which many are unusual. The
frontal is omitted from the orbital margin, and the
postorbital is singularly large, covering a major
part of the temporal roof. The medially directed
process of the jugal is reduced and does not contact
either the palatine or the pterygoid, as is normal
in turtles. As the horizontal palatine process of the
maxilla is so narrow that it is nearly absent, the
palatine extends laterally to the labial ridge of the
maxilla, and there is only a primary palate. The
crista supraoccipitalis, which is the attachment site
for tendons of the adductor mandibulae externus
and normally the most prominent external feature of
the supraoccipital, is relatively small. The fact that
the maxillaries and premaxillaries do not border the
internal nares, but slender processes of the palatines
and vomer do, was used by Dollo (1903) to argue that
an ancestor of Dermochelys had a secondary palate
similar to that of the cheloniids.
Dermochelys coriacea shares a number of peculiar
features with the cheloniids. The foramen palatinum
posterius is absent (Gaffney 1979). In the quadrate,
the incisura columellae auris, containing the single
ear bone, is relatively open. There is no contact
between the maxillae and pterygoid. The internal
carotid artery gives off the palatine branch from
within the cranial cavity, not closely surrounded by
Chapter 1: Identity 17
bone within the canalis caroticus; this is related to
several features in the pterygoid involving reduced,
or absent, bony roofs or canals and the absence
of foramina (Nick 1912, Albrecht 1976, Gaffney
1979). As in some cheloniids, the basioccipital is
exposed dorsally between the exoccipitals for the
length of the condylus occipitalis (Gaffney 1979).
The processus trochlearis oticum of the prootic
is highly reduced. As in the cheloniids, the taenia
intertrabecularis develops in the embryo; however,
unlike the cheloniids, in D. coriacea it does not
ossify, whereas the dermal posterior parasphenoid
blastema does and persists as a rudiment in the
endochondral basisphenoid (Nick 1912, Pehrson
1945, Gaffney 1979). Versluys (1907) was first to
show, despite long standing opinions to the contrary,
that the parasphenoid does exist in Dermochelys,
although this was not immediately accepted (Fuchs
1910, Versluys 1910).
In addition, D. coriacea has several unique features
in its skull. The squamosal does not reach the
processus paroccipitalis of the opisthotic (Gaffney
1979). This is the only cryptodire known to lack an
ossified epipterygoid, evidently from neoteny (Nick
1912; Gaffney 1975, 1979). Neither the prootic nor
the pterygoid contacts the rudimentary processus
inferior parietalis; pterygoid contact with the
anteroventrolateral portion of the prootic is also
absent (Gaffney 1979).
Several other cartilaginous features of the skull are
noteworthy. The brain case, with highly reduced
bony walls, is secondarily closed by cartilage (Nick
1912). Rostral cartilage, an extension of the nasal
septum, develops in embryos (Pehrson 1945). The
occipital condyle remains cartilaginous throughout
life (Hay 1908).
The sclerotic ossicles commonly number 14, but
may be as few as seven, when there may be a gap
in the anterodorsal part of the ring. Usually the
number of ossicles in each eye is equal, and evidently
individual ossicles may expand to fill gaps in the ring.
Neighboring ossicles may be subimbricate or fused
(Deraniyagala 1932, 1939, 1953). In 31 turtles (6
hatchlings, 2 small juveniles: 17, 27 cm CCL, and 23
subadults and adults [9♀, 8♂, 6 unknown]: 122–173
cm CCL) examined by Avens and Goshe (2008),
there were 11–14 ossicles per eye (mean = 12); there
was no discernible gap in the ring (L.R. Goshe, pers.
comm.).
The mandible also exhibits unique or highly unusual
features; the dentary contacts only the surangular
and the angular, rather than five different bones.
Only the labial ridge is developed on the dentary, for
the linguinal ridge is absent (Gaffney 1979). There
is no depression in the lateral surface of the dentary
for attachment of the adductor mandibulae externus.
The coronoid is absent; the articular is unossified;
and the prearticular does not contact any other bone,
for it is isolated by the cartilaginous articular.
Post-Cranial Skeleton.—A thorough and detailed
study of the trunk, limb and dermal skeleton was
done by Völker (1913). The vertebrae number:
8 cervical, 10 dorsal, 2 sacral and 18 caudal
(Deraniyagala 1939) [n.b. Völker (1913) reported
one more sacral and one less caudal]. The neck
is relatively short, evidently from secondary
shortening; and although some vertebrae are united
by thick cartilaginous pads and strong fibrous tissue,
they show articulations typical of the Cryptodira
(Versluys 1913, Völker 1913). However, Hay (1922)
refused to accept that this, or the resemblance of
vertebrae with those of other sea turtles pointed
out earlier by Vaillant (1877), had phylogenetic
significance. As is usual for the Cryptodira, the
IVth vertebra is biconvex, those anterior to it are
opisthocoelus, those posterior are procoelus. The
joint between VI and VII tends toward immobility
and sometimes it is almost fused; the joint between
VII and VIII is highly variable, sometimes biconvex
(Williams 1950).
Cervical ribs are reduced in size, cartilaginous
and generally fused to the vertebrae (Romer 1956)
(Appendix C). Of the 10 dorsal ribs, the first pair are
short and the last pair are vestigial; the others have
thin phalanges on both anterior and posterior edges
which are widest medially. Compared to the costal
bones of other turtles, the ribs of this species are
narrow and feeble, but Hay (1898, 1908) thought that
their flattened form, with jagged edges, showed that
they had once been fused to costal plates. The caudal
vertebrae are procoelous and lack chevron bones
(Deraniyagala 1939).
Several features distinguish the humerus. Unlike in
most other sea turtles, the ectepicondylar foramen
persists throughout life, and does not open to form a
groove. The deltopectoral crest projects far laterally,
and is associated with a strong transverse line of
sites for muscle attachment on the ventral surface of
the shaft. The lateral tubercle is poorly developed.
Hind limb elements, femur, tibia and fibula, are
somewhat flattened dorso-ventrally and relatively
short (Romer 1956). The phalanges are elongate
and lack condyles. The carpus has only one central,
although a rudiment of the second radial central may
be present in young animals (Versluys 1913, Völker
1913) (Appendix C).
The epiphyses of the long bones remain cartilaginous
and unossified throughout life, and they are highly
vascularized from the epiphyses to the diaphyses
by conspicuous perichondral and transphyseal
vessels that traverse relatively thin physeal plates
(Rhodin et al. 1981). Conspicuous endochondral and
periosteal bone cones are thought to be unchanged
throughout life from remodeling. These chondro-osseous
characteristics are comparable to those in
marine mammals and indicate the potential for rapid
growth and an active metabolic rate (Rhodin 1985).
The elements of the pectoral girdle are relatively
robust, with a massive coracoid. More remarkable
is the pelvic girdle, which lacks the usually large
18 Synopsis of the Biological Data on the Leatherback Sea Turtle
thyroid fenestra in the puboishiadic plate, and
instead has a pair of small foramina. The plate
remains largely cartilaginous. A well developed
epipubis is unique in having a medial fenestra
(Versluys 1913, Völker 1913, Deraniyagala 1939,
Romer 1956).
The normal testudine dermal skeleton (termed
“thecal”) is extremely reduced; only a bat-shaped
nuchal bone is present in the carapace, and this
is separated from the outer shell by a layer of
connective tissue (Versluys 1913). Thecal elements
of the plastron are also reduced; instead of the
usual solid plate, there is a flimsy ring around the
periphery, although there is some overlap in the
eight splint-like bones. The entoplastron is absent,
except as a cartilaginous vestige in some embryos
(Deraniyagala 1939). Both the carapace and the
plastron have been described and illustrated by
Völker (1913), Deraniyagala (1939) and Brongersma
(1969).
In contrast, “epithecal” dermal elements are highly
developed. About seven months after hatching,
osteoderms begin to appear along the keels.
Tectiform platelets dominate, but their line is
interrupted by flat ossicles. Gradually, smaller, flat
ossicles appear between the keels of the carapace,
until virtually the entire dorsal surface is covered
by a mosaic of interlocking ossicles (Appendix C).
Osteoderms on the plastron only develop under
the keel ridges, and even then only posterior to
the epiplastral region and in interrupted lines. The
osteoderms on the neural ridge of an adult female
only made up 5 mm of the total 41 mm thickness.
Sometimes described as “polygons” the dermal
ossicles are irregular in shape; those from between
ridges are rarely more than a centimeter wide
(Deraniyagala 1939) (see Chapter 3, Embryonic
and hatchling phases, Embryonic phase, below). A
detailed description of the epithecal mosaic is given
by Broin and Pironon (1980).
Compared with other, extinct dermochelyids, the
plastral armor of D. coriacea is highly reduced,
and Deraniyagala (1930, 1934, 1939) concluded that
the process of reduction in osteoderms appears
to be proceeding dorsally in the extant form. The
epithecal elements of the plastron are restricted
almost completely to six longitudinal rows.
Proceeding laterally from the paramedial rows, the
osteoderms often become larger but less numerous.
In two of the three specimens examined in detail
by Brongersma (1969; two adult-sized males and a
subadult of unspecified sex), the osteoderms of the
plastron showed signs of abrasion and in all cases
some platelets had evidently fallen out. There was no
explanation for this.
Descriptions of the remarkable anatomical features
of the shell and discussions of their phylogenetic
relevance have been common and lively during
the earlier part of the last century (see Versluys
1913, 1914; Hay 1922). Pritchard and Trebbau
(1984) hypothesized that a mosaic of small bones
allows the turtle to grow in size more rapidly than
would be possible with the normal, heavily ossified
turtle shell. In this respect, comparisons with
other taxa (e.g., Glyptodonts, Recent Edentates)
that also have a mosaic of dermal osteoderms may
prove enlightening.
Versluys (1913) summarized information from
numerous detailed osteological studies to conclude
that the epithecal shell of Dermochelys is not a de
novo structure, but has homologues in both living
and fossil turtles. Völker (1913) argued that the
peripherals (equal to the “marginal bones”) of the
typical thecophoran shell are epithecal in origin.
This contrasts with Dollo’s (1901) view that epithecal
elements are unique to the Dermochelyidae, and
also with Hay’s (1922) view that epithecal elements
are found in a variety of testudinates, living and
fossil, but nonetheless that Dermochelys is in a
distinct suborder. Romer (1956) listed a variety of
reptiles, including turtles extant and fossil, that have
well developed osteoderms, and although there is
disagreement about the evolution of dermal ossicles,
he concluded, together with earlier authors, that
epithecal components are included in the shells of
other turtles.
An earlier system of referring to “subdermal”
and “true dermal” elements to the shell (Hay
1898, 1908) was rejected in favor of “thecal” and
“epithecal” because both classes of elements arise
from the dermal layer (Versluys 1913, Völker 1913).
Likewise, describing the carapace of Dermochelys
as “dermal” and that of the other turtles as
“skeletal” (Deraniygala 1932) is imprecise. Also
inaccurate is the reference to a “primitive dermal
skeleton” (Villiers 1958). Although the carapace of
Dermochelys is unique among living Testudines, it
is not usual to refer to it as a “pseudo-carapace” or
“pseudo-dossière” (Fretey 1978, 1982; Fretey and
Frenay 1980). Useful illustrations of the postcranial
skeleton are in Deraniyagala (1939, 1953).
Cytomorphology
The calculated volume of an erythrocyte (> 900
μm3) is more than 10 times the volume of a human
corpuscle (Frair 1977a). Red cell counts ranged
from 447 to 547, averaging 0.503 x 106 μ1 –1; and
packed cell volumes ranged from 32 to 49, with
a mean of 42.3 cm3 per 100 cm3 [0.423 L per L]
(with no significant relation to carapace length).
In comparison with other species of sea turtles,
the counts were higher and the mean corpuscular
volume (MCV) was lower (Frair 1977b).
Montilla et al. (2008) reported hematological values
in 13 gravid females nesting at Querepare Beach,
Venezuela. Counting of red (RBC) and white (WBC)
blood cells were conducted using the Natt and
Herricks technique, with the following results: mean
RBC value = 0.33x103 μ1 –1 ± 0.06 (0.25–0.43); mean
WBC value = 3.15x103 μ1 –1 ± 0.7 (1.9–4.6); PCV
= 35.4% as determined through centrifugation;
and Mean Corpuscular Volume = 1076.9 fL ±
158.3 (878–1360). WBC differential counts were
Chapter 1: Identity 19
performed manually using light microscopy and
Diff-Quik stains; four types of WBC were identified
(heterophils, lymphocytes, eosinophils, monocytes).
Deem et al. (2006) reported similar values for
PCV, RBC and WBC from 28 nesting leatherbacks
in Gabon.
Biochemistry
Chemical analyses of blood (postmortem specimens)
showed the following concentrations: non-protein
nitrogen = 109 mg dL–1; urea nitrogen = 70 mg dL–1;
uric acid = 4 mg dL–1; chloride = 596 mg dL–1; total
protein = 4.77 g %; albumin = 2.21 g %; globulin =
2.40 g %; fibrinogen = 0.12 g % (Dunlap 1955). These
blood concentrations represent: 50% of the value
of urea in urine; 1.25% of the uric acid in urine; and
118.49% of the chloride value in urine.
Deem et al. (2006) reported plasma biochemistry
values from 18 adult female leatherbacks nesting in
Gabon, including the following ranges: glucose (55–
95 mg dL–1), sodium (124–148 mmol L–1), potassium
(2.8–5.1 mmol L–1), CO2 (18–25 mmol L–1), blood
urea nitrogen (2–13 mg dL–1), total protein (3.0–6.0
g dL–1), albumin (1.0–2.4 g dL–1), globulins (1.7–3.8
g dL–1), cholesterol (136–497 mg dL–1), triglycerides
(232–473 mg dL–1), calcium (4.4–10 mg dL–1),
phosphorus (8.9–14 mg dL–1), uric acid (0.2 mg dL–1),
aspartate aminotransferase (94–234 U L–1), creatine
kinase (20–7086 U L–1) and others. Harms et al.
(2007) reported similar values, with the exception of
higher calcium (10.1–16.8 mg dL–1) and phosphorus
(13.1–20.2 mg dL–1), from 13 nesting leatherbacks
in Trinidad, and also included measurements of
chloride (104–117 mmol L–1), lactate (0.9–4.2 mmol
L–1), and others.
Tests of immunoprecipitation with antiserums
show that D. coriacea is distinct from the hard-shelled
sea turtles, but more like them than other
turtles (Frair 1979). Similar results were obtained
with electrophoresis and immunoelectrophoresis
of serums, and it was reported that Dermochelys
has the second fastest moving anodal line (albumin)
(Frair 1982). These studies resulted in the conclusion
that D. coriacea is in the same family as the other
Recent sea turtles.
Molecular and functional properties of the ferrous
and ferric derivatives of the native and PCMB-reacted
main myoglobin component (Mb II) have
been compared with those of other monomeric
hemoproteins, and found to be similar to those of
sperm whale myoglobin (Ascenzi et al. 1984).
Studies of six tryptic peptide patterns (hemoglobin
fingerprints) in six species of turtles showed that
Dermochelys often has the simplest pattern, with
fewer peptide spots. It was concluded that this turtle
arose from the cheloniids because its globins were
said to be most similar to those of cheloniids (Chen
and Mao 1981). However, the results presented do
not show this unequivocally. Cohen and Stickler
(1958) reported that this turtle, like several other
species, lacks human-like albumen proteins in
the serum. Frair (1969) found that compared with
fresh serum, serum that has been stored at 4°C for
10 years loses about one third of its reactivity in
immunological reactions. This effect was similar to
the results with freshwater turtles, but more marked
than with other species of sea turtles.
Two unsaturated fatty acids are concentrated in
depot fat: the monoene trans 16:1tw10 (trans-
6-hexa-decenoic acid) and the polyene 20:4w6
(Ackman et al. 1971, 1972). In turtles, the monoene
is only reported from marine species, in which
the polyene is also unusually prominent; as both
of these fatty acids are concentrated in jellyfish,
they are thought to originate exogenously in the
turtles, from coelenterate food items (Ackman et
al. 1971, Joseph et al. 1985). The unusually high
concentration of another long-chained unsaturated
acid, notably 20:1w7, may result from the same
food chain effect, as may the occurrence of 22:4w6
(Ackman et al. 1971). An absence of 16:1w9 and a
relatively low proportion of 18:1w7 to 18:1w9 was
taken as evidence that metabolic chain shortening
is not as common as with other turtles, particularly
freshwater species. Nearly comparable proportions
of the saturated fatty acids 12:0 (lauric) and 14:0
occur in fats of Dermochelys (Ackman et al. 1971)
and these are thought to have been converted from
jellyfish carbohydrates (Joseph et al. 1985).
The diversity of chemical compounds found in the
oils is unusual for a marine animal (Ackman and
Burgher 1965). Analysis of oil specimens from Sri
Lanka and Japan showed saponification values of
199.6 and 181.3, respectively and iodine content
of 103.8% and 128.1%, respectively (Deraniyagala
1953). Antibiotic effects have been demonstrated in
Dermochelys oil (Bleakney 1965), and this potential
warrants detailed investigation.
Karyotype.—In an early review of cryptodirian
chromosomes, Bickham and Carr (1983) could not
report any data for D. coriacea. Medrano et al.
(1987) examined chromosomal preparations from
kidney, spleen, and lung cells of three leatherback
hatchlings from artificially incubated eggs. Based
on incubation temperature, all were presumed
to be males. Using the same nomenclature and
categorization as Bickham and Carr (1983), they
arranged chromosome types as follows: group
A consists of metacentric and submetacentric
chromosomes, group B consists of telocentric
and subtelocentric chromosomes, and group C
consists of microchromosomes. They reported
that leatherbacks have a diploid number of
56 chromosomes and identified seven pairs of
group A macrochromosomes, 5 pairs of group
B macrochromosomes and 16 pairs of group
C microchromosomes. No heteromorphic sex
chromosomes were found.
Medrano et al. (1987) concluded that this is the
same chromosomal configuration shown by other
extant sea turtle taxa (2n = 56; c.f. Bickham 1981,
1984); noted that distinct adult morphological
20 Synopsis of the Biological Data on the Leatherback Sea Turtle
characteristics (e.g., shell constitution: Romer 1956;
chondro-osseous morphology: Rhodin et al. 1981)
represent derived characters; and supported the
classifications of Gaffney (1975) and Bickham and
Carr (1983) that there are two living families of sea
turtle, the Dermochelyidae and the Cheloniidae (see
Taxonomic Status, above).
Chapter 2: Distribution 21
Chapter 2: Distribution
Total Area
No other reptile has a geographic range as great
as that of the leatherback sea turtle (Table 6,
Figure 1). The species is known to nest on every
continent except Europe and Antarctica, as well
as on many islands in the Caribbean and the
Indo-Pacific. Reliable at-sea sightings confirm
a range that extends from ~71°N (Carriol and
Vader 2002) to 47°S (Eggleston 1971). A record
of Dermochelys in the Barents Sea is often but
erroneously attributed to Bannikov et al. (1977),
who reported the species from the Bering Sea; in
fact, the Barents Sea sighting was of a loggerhead
sea turtle (Caretta caretta) (see Brongersma
1972, Kuzmin 2002).
In the Western Atlantic, a regular summer
population appears in the Gulf of Maine and as far
north as Newfoundland (48°N) (Bleakney 1965,
Brongersma 1972, Lazell 1980, Shoop et al. 1981),
and there is also a record from Labrador (56°45ʹN)
(Threlfall 1978). There are numerous records from
as far south as Rio de la Plata and Mar del Plata,
Argentina (38°S) (Freiberg 1945, Frazier 1984).
Eastern Atlantic records include northern Norway
(68°46ʹN), Iceland and the Baltic Sea (Brongersma
1972). An adult female caught at Skreifjorden,
Seiland, Finnmark in northern Norway in
September 1997 (~71°N, 23°E) is the northernmost
record for the species (Carriol and Vader 2002)
and the range extends as far south as Angola and
Cape Town (34°S) (Hughes 1974a). European and
Mediterranean sightings are summarized by Casale
et al. (2003) and Frazier et al. (2005).
Indian Ocean records range from the northern limits
of the Red Sea (28°N) (Frazier and Salas 1984a) to
the waters of the Southern Ocean off South Africa
(41°48ʹS, 22º18ʹE) (Hughes et al. 1998). There are
numerous records from Southeast Asia (Polunin
1975, Hamann et al. 2006a), but fewer from Australia
and Tasmania (Limpus and McLachlan 1979, Tarvey
1993). Sightings extend into New Zealand, some as
far south as Foveaux Strait (47°S), the southernmost
record for the species (Eggleston 1971).
In the Northwest Pacific, there are records
from the Japanese coast, some as far north as
44°N (Nishimura 1964a, 1964b), from near Mys
Povorotnyg on the Soviet coast (~44°N) (Taranetz
Table 6. Published records that define the known northern and southern geographic range for successful
egg-laying by leatherback sea turtles.
Region Northern Nesting Record Southern Nesting Record Reference
Eastern Pacific Ocean
San Felipé, Baja California,
Mexico (30º 56’ N) Mulatos, Colombia (2° 39’ N)
N: Caldwell (1962)
S: Amorocho et al. (1992)
Western Atlantic Ocean
Assateague Island National Seashore,
Maryland, USA (38º N) 1
Torres, Rio Grande do Sul,
Brazil (29º S)
N: Rabon et al. (2003)
S: Soto et al. (1997)
Eastern Atlantic Ocean
“at the entrance of Bolon de Djinack,”
Senegal (13º 35’ N, 16º 32’ W) 2
between Cabo Ledo (9º 39’ S, 13º 15’ E)
and Cabo de São Bráz (9º 58’ S, 13º 19’ E),
Angola 3
N: Dupuy (1986)
S: Carr & Carr (1991)
Western Indian Ocean
Quirimbas Archipelago National Park,
Mozambique (12º 19’ S, 40º 40’ E)
Storms River mouth, Western Cape,
South Africa (34º 01’ S, 23º 56’ E) 4
N: Louro (2006)
S: George Hughes, in litt. 4
October 2009
Eastern Indian Ocean
West Bay, Little Andaman Island, India
(10º 38’ N, 92º 25’ E) 5
Alas Purwo National Park, Jawa,
Indonesia (8° 40’ S, 114° 25’ E)
N: Choudhury (2006)
S: Adnyana (2006)
Western Pacific Ocean
Jamursba-Medi, Papua, Indonesia
(0º 20’–0º 22’ S, 132º 25’–132º 39’ E)
Newcastle, New South Wales, Australia
(32° 55’ S, 151° 45’ E) 6
N: Adnyana (2006)
S: Limpus (2006)
1 This record is an isolated event not associated with an active leatherback nesting beach, and is not mapped in Figure 1
2 Márquez (1990) described nesting in Mauritania [north of Senegal] as “minor and solitary,” but no locations were given
3 Huntley (1974, 1978) made similar observations “south of Luanda,” but no locations were given
4 This record is an isolated event not associated with an active leatherback nesting beach, and is not mapped in Figure 1
5 Jones (1959) reported a daylight nesting near Kozhikode (11° 15’ N, 75° 47’ E), but nesting on the Indian mainland is extremely rare
6 This record is an isolated event not associated with an active leatherback nesting beach, and is not mapped in Figure 1
22 Synopsis of the Biological Data on the Leatherback Sea Turtle
1938), and from near Mys Navarin in the Bering Sea
(~62°N) (Terentjev and Chernov 1949, Bannikov
et al. 1971, 1977). In the Eastern Pacific, records
extend north to British Columbia (MacAskie and
Forrester 1962) and the Gulf of Alaska (61°N)
(Hodge 1979) and south to Quinteros, Chile (33°S)
(Frazier and Salas 1984b).
Despite its extensive range, distribution is far from
uniform and large nesting colonies are rare. In the
Western Atlantic, nesting occurs as far north as
Assateague Island National Seashore, Maryland
(38ºN) (Rabon et al. 2003) and as far south as Torres,
Rio Grande do Sul, Brazil (29ºS) (Soto et al. 1997).
In the most complete assessment, leatherbacks
laid eggs on 470 of 1311 known nesting beaches in
the Western Atlantic, but only 2% (10/470) received
more than 1000 nesting crawls per year (Dow et al.
2007). The largest colonies are located in French
Guiana-Suriname, where a “…stable or slightly
increasing…” population laid an estimated 5029
[1980] to 63,294 [1988] nests per year from 1967 to
2002 (Girondot et al. 2007), and Trinidad, where an
estimated 52,797 and 48,240 nests were laid at the
nation’s three largest nesting beaches in 2007 and
2008, respectively, and the population is also believed
to be stable or slightly increasing (SAE).
In the Eastern Atlantic, “…widely dispersed but
fairly regular…” nesting occurs between Mauritania
in the north and Angola in the south, but only Gabon,
with about 5865 to 20,499 females nesting annually
(Witt et al. 2009), is reported to have a large colony1.
Field surveys are incomplete, but literature notes
on the northern and southern boundaries of egg-laying
in this region describe nesting in Mauritania
as “…minor and solitary…” (Márquez 1990) and,
to the south, as dispersed over “…some 200 km of
coast south of Luanda…” in Angola (Hughes et al.
1973, also Weir et al. 2007). All available reports are
summarized by Fretey (2001).
In the Western Indian Ocean, the nesting colonies
of South Africa have been actively studied since
the 1960s. Regular and monitored leatherback
nesting is normally restricted to north of the St.
Lucia Estuary (28º 22ʹS, 32º25ʹE) and some 200
km to the Mozambique border, with “…occasional
nesting females encountered on beaches south
of St. Lucia…” and a southernmost record at
the Storms River mouth (34º01ʹS, 23º56ʹE) in
the Western Cape (G.R. Hughes, pers. comm.).
There was a “…gentle but steady increase…” in
the numbers of leatherbacks nesting in the 56-km
survey area in Tongaland (KwaZulu-Natal) from five
females in 1966–1967 to 124 females in 1994–1995
(Hughes 1996).
1 For conversion between nests laid per year and females
nesting annually, the typical clutch frequency is 5 to 7
nests per female per reproductive year.
Figure 1. Global distribution of the leatherback sea turtle, including northern and southern oceanic range
boundaries and sites representative of the species’ current nesting range. Extreme northern and southern
records (see Table 6 for coordinates) may not represent persistent nesting grounds, but represent known
geographic boundaries for successful reproduction. Map created by Brendan Hurley (Conservation
International).
Chapter 2: Distribution 23
The IUCN (2001) recognizes Sri Lanka and the
Andaman and Nicobar Islands as the last three
areas in Southeast Asia with significant nesting;
the colony in Nicobar is one of the few that exceeds
1000 individuals in the Indo-Pacific region (Andrews
2000). An estimated 5000 to 9200 nests are laid each
year among 28 sites in the Western Pacific, with
75% of these concentrated at only four sites along
the northwest coast of Papua, Indonesia (Dutton et
al. 2007).
No major nesting is recorded in Australia. As
summarized in Department of the Environment,
Water, Heritage and the Arts (2008): low density
nesting (1–3 nests per year) occurs in southern
Queensland (Limpus and MacLachlan 1979,
1994) and the Northern Territory (Limpus and
MacLachlan 1994, Hamann et al. 2006a); some
nesting has occurred in northern New South Wales
(NSW) near Ballina (Tarvey 1993), although no
nesting has been reported in Queensland or NSW
since 1996 (Hamann et al. 2006a); and nesting in
Western Australia is still unknown or unconfirmed
(Prince 1994).
In the Eastern Pacific, only remnant populations
remain. Mexico, until recently with the largest
nesting population in the world (~75,000
reproductively active females: Pritchard 1982),
recorded 120 nests (combined) at four index
monitoring sites during 2002–2003 (Sarti M. et al.
2007). Contemporary nesting is documented from
Colombia (Mulatos, 2°39ʹN: Amorocho et al. 1992)
north to the Baja California peninsula, Mexico (San
Felipe, 30º56ʹN: Caldwell 1962 in Seminoff and
Nichols 2007).
Both major and minor nesting areas are largely
confined to tropical latitudes; exceptions include
Florida (United States) and KwaZulu-Natal (South
Africa). Recent regional summaries are available for
the Western Atlantic (Stewart and Johnson 2006,
Dow et al. 2007, Turtle Expert Working Group 2007),
Eastern Atlantic (Fretey 2001, Fretey et al. 2007a),
Indian Ocean and Southeast Asia (Humphrey and
Salm 1996, Zulkifli et al. 2004, Hamann et al. 2006a,
Shanker and Choudhury 2006), and Australia
(Department of the Environment, Water, Heritage
and the Arts 2008), as well as for the Western (Kinan
2002, 2005; Dutton et al. 2007), Northern (Eckert
1993) and Eastern (Spotila et al. 1996, Sarti M. et al.
2007) Pacific Ocean.
Pritchard and Trebbau (1984) summarized global
nesting records, including notes on geographic
variation. In a review mandated by the United
States Endangered Species Act (ESA) of 1973, the
United States National Marine Fisheries Service
and the United States Fish and Wildlife Service
(2007) provided an updated global overview of
current species status, including nesting records.
Figure 2. Generalized leatherback sea turtle life cycle. Source: Chaloupka et al. (2004:150).
24 Synopsis of the Biological Data on the Leatherback Sea Turtle
Differential Distribution
In order to successfully complete the life cycle
(Figure 2), the leatherback sea turtle relies on
developmental habitats that include the nesting
beach, as well as coastal and pelagic waters.
Hatchlings
The post-hatchling habitat remains obscure. In
a thorough review of the pelagic stage of post-hatchling
sea turtle development, Carr (1987) found
no evidence that young Dermochelys, in contrast
to the young of other sea turtle genera, associate
with Sargassum or epipelagic debris. The striking
pattern of light stripes on a black background
would appear to make the hatchlings conspicuous in
virtually any habitat, although the counter-shading,
which develops as the animal grows, might offer
some crypsis (Pritchard and Trebbau 1984).
Persistent swimming in captivity prompted Carr and
Ogren (1959) to propose that hatchling leatherbacks
spend the first hours or days following emergence
from the nest in steady travel away from their natal
beach. Hall (1987) followed hatchlings offshore
from Puerto Rico, noting that they “…swam almost
continuously…” in a relatively undeviating course
away from land, and Fletemeyer (1980) terminated
his attempts to follow hatchlings during their initial
journey offshore after becoming exhausted by
their unrelenting activity. In the first quantified
study, Wyneken and Salmon (1992) observed
that having entered the sea, hatchlings swam
unhesitatingly away from land—a period referred
to as ‘frenzy,’ during which time the small turtles
swim continuously for the first 24 hours before
undertaking a diel swimming pattern.
The relatively limited range of swimming styles
exhibited by leatherback hatchlings and adults may
reflect an oceanic lifestyle, i.e., the need to swim
steadily over great distances in order to prey on
surface plankton, specifically jellyfish. Shortly after
entering the ocean, hatchlings are capable of diving
(Deraniyagala 1939, Davenport 1987, Price et al.
2007). Salmon et al. (2004) reported that leatherback
hatchlings between 2–8 weeks of age dived deeper
and longer with age and foraged throughout the
water column on exclusively gelatinous prey.
Juveniles and Subadults
There are few data relevant to the distribution of
leatherback juveniles and subadults. Deraniyagala
(1936a) suggested that they remain in the open
ocean, based on the sighting of a juvenile 20 km from
shore. Eckert (2002a) summarized data gleaned
from published sources, stranding databases, fishery
observer logs and museum records on the location,
date, sea temperature and turtle size for 98 small
(< 145 cm) specimens from around the world. He
concluded that juveniles < 100 cm CCL occur only
in waters warmer than 26°C; in contrast, turtles
slightly larger than 100 cm were found in waters as
cool as 8°C. A juvenile (30.5 cm CCL), feeding on
pelagic tunicates (Class Thaliacea), stranded near
death in Western Australia in July 2002 after having
been “…entrained for some extended time…” in a
cold water mass (Prince 2004).
Morphological and physiological characteristics
enhance the leatherback’s ability to stay warm.
These features include a cylindrical body form,
large body mass, thick fatty insulation and
countercurrent circulation (Greer et al. 1973); adults
may also have temperature independent cellular
metabolism (Spotila and Standora 1985, Paladino
et al. 1990, Spotila et al. 1991, Penick et al. 1998).
It is possible that large size (> 100 cm CCL), in
reducing the surface area to mass ratio, creates
a thermal inertia regime that enables forays into
cold water (see Chapter 3, Juvenile, subadult and
adult phases, Hardiness, below). If leatherbacks
are able to efficiently retain metabolically generated
heat, as proposed by Penick et al. (1998), then one
interpretation of the distributional data is that this
capacity is developmentally induced and that heat
generation is physiological rather than simply a
function of morphology.
The relationship between the distribution of juvenile
leatherbacks and temperature is an important clue
to understanding life history. It appears certain that
leatherbacks spend the first portion of their lives in
tropical waters, venturing into cooler latitudes only
after reaching 100 cm CCL (Eckert 2002a). As is the
case with adults, the distribution of juveniles and
subadults is likely closely linked to the distribution
and abundance of macroplanktonic prey. For
example, the fact that jellyfish “…were abundant
throughout the study area…” may explain the
presence of subadult and adult leatherbacks off the
coast of Angola (Carr and Carr 1991).
Adults
As an adult, Dermochelys has the most extensive
biogeographical range of any extant reptile,
spanning ~71°N (Carriol and Vader 2002) to 47°S
(Eggleston 1971). Nesting occurs in primarily
tropical latitudes on every continent except Europe
and Antarctica, as well as on many islands in the
Caribbean and the Indo-Pacific; large nesting
colonies are rare (see Total area, above).
Foraging, mainly on gelatinous cnidarians and
tunicates (see Chapter 3, Nutrition and metabolism,
Food, below), is reported both on the continental
shelf and in pelagic waters. Long distance migration
between foraging and nesting grounds is the norm
(see Chapter 3, Behavior, Migrations and local
movements, below).
Chapter 2: Distribution 25
Determinants of
Distributional Changes
There is no information on the geography, sequence,
timing, or impetus for distributional changes related
to developmental habitats for young Dermochelys.
Nothing is known of the dispersal or distribution of
post-hatchlings in the open sea. Oceanic distribution
of juveniles (and adults) most likely reflects the
distribution and abundance of macro-planktonic
prey, as well as preferred thermal tolerances.
According to empirical data collated by Eckert
(2002a), juveniles < 100 cm CCL are likely confined
to ocean waters warmer than 26°C.
Reproductively active females (and recent data
show males, as well) arrive seasonally at preferred
nesting grounds in (mainly) tropical latitudes, while
non-breeding adults and subadults range further
north and south into temperate zones seeking areas
of predictable though often ephemeral patches of
oceanic jellyfish and other soft-bodied invertebrates.
Long-distance movements are not random but
regular in timing and location. While the proximal
impetus is unknown, the turtles seem to possess
some innate awareness of where and when profitable
foraging opportunities will occur (see Chapter 3,
Behavior, Migrations and local movements, below).
Hybridization
No hybridization involving Dermochelys is known.
26 Synopsis of the Biological Data on the Leatherback Sea Turtle
Chapter 3: Bionomics and Life History
Reproduction
Sexual Dimorphism
There is no apparent sexual size dimorphism in adult
leatherbacks (James et al. 2005a); notwithstanding,
by far the largest specimen on record is that of a
male captured off the coast of Wales, U.K. (916 kg,
Morgan 1990). The largest females on record are
non-breeding adults weighed after having been
captured incidentally in fisheries off South Africa
(646 kg, Hughes 1974a) and Nova Scotia (640 kg,
James et al. 2007). Sexual size dimorphism occurs
in various reptile taxa, including sea turtles (Miller
1997). Leatherbacks may represent a departure
from this model, but additional data, especially from
females during non-reproductive years and from
adult males, are needed.
Apart from sexual size dimorphism, anatomical
dimorphisms exist that permit visual distinction
between adult males and females. The tail of the
adult male is much longer than that of the female,
and the cloaca extends further beyond the posterior
tip of the carapace (James 2004, James et al. 2007).
Furthermore, the adpressed hind limbs extend
posteriorly to the cloaca only in male leatherbacks,
whereas in females the tail barely reaches half-way
down these limbs (Deraniyagala 1939, Reina et
al. 2005). Deraniyagala (1939) described the male
as having a concave plastron, narrow hips, and a
shallow body depth (vertical height of carapace and
plastron when the animal is on land) relative to the
female, and speculated that the pronounced terminal
osteoderm on each ventral ridge on the male might
assist in maintaining his position on the female
during copulation (as mating is rarely observed, this
speculation is difficult to confirm).
No information is available regarding sexual
dimorphism in juvenile size classes.
Age at Maturity
Age at maturity has not been conclusively
determined, but recent estimates (Avens and Goshe
2008, Avens et al. 2009) extend those posed by
earlier studies.
Direct field measurements are problematic;
therefore, inferential or correlative analyses have
been employed to generate estimates of leatherback
age at maturity. For example, estimates have been
made based on extrapolations from growth rates of
post-hatchlings and young juveniles held in captivity
(Deraniyagala 1939, Birkenmeier 1971, Jones
2009), from histological and skeletochronological
analyses (Rhodin 1985, Zug and Parham 1996,
Avens et al. 2009), population trend analysis of
reproductively active females (Dutton et al. 2005),
and inference of generation time through DNA
fingerprinting (Dutton et al. 2005) (Table 7). These
estimates generally indicate that Dermochelys
may reach sexual maturity at an earlier age than is
characteristic of other sea turtle genera (excepting
Lepidochelys). In the most comprehensive analysis
to date (a skeletochronological assessment based on
eight known-age, captive reared turtles and 33 wild
leatherbacks from the Atlantic, spanning hatchling
to adult), Avens et al. (2009) estimate age at maturity
to be similar to that of other large sea turtle genera
(2–3 decades or longer).
In the absence of field measurements, indirect
techniques such as analyses of bone growth
patterns, with a known or inferred temporal
component, can be used to generate length-age
data pairs. Specifically, patterns of bone growth and
remodeling that are manifested in lines of arrested
growth (LAGs), or growth rings, may represent
annual cycles of active growth and cessation of
growth. These generated length-age data pairs can
then be coupled with growth functions to estimate
age at mat