Dermochelyidae

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This turtle is the largest of all living turtle species.

The family Dermochelyidae contains a single species, Dermochelys coriacea. It occurs in oceans worldwide. It has physiological adaptations that prevent the loss of body heat, allowing it to establish a range more poleward than the other sea turtles (Cheloniidae).

Dermochelyids are the largest extant turtles, reaching sizes of 244 cm in carapace length and over 800 kg. The carapace is a composite of osteoderms embedded in a leathery skin, hence the common name. Seven keels are present on the carapace. The head cannot be fully retracted within the shell, and the fourth cervical vertebra is biconvex.

Dermochelys coriacea is pelagic and feeds almost exclusively on jellyfish. Other prey may be incidentally taken, but the jaws are very weak and incapable of masticating hard prey. Virtually no natural predators are known for adult leatherbacks, although sharks, killer whales, and jaguars have been reported to injure adults. Eggs and hatchlings are predated by members of every class of vertebrates and numerous invertebrates.

Other than aspects of nesting, little is known about the general or reproductive behavior of the Dermochelyidae. Females reproduce on a multiyear cycle, but may oviposit as many as six times within a single season. Between 50 and 170 eggs comprise a typical clutch.

It is relatively certain that the Cheloniidae form a monophyletic group with the Dermochelyidae, referred to as the Chelonioidea. The characters that unite these two families include elongation of digits III and IV, flattening of the carpals and tarsals, and articulation between the neural spine of the eighth cervical vertebra and the ventral surface of the nuchal bone.

Dermochelys coriacea is a federally endangered species protected under the Endangered Species Act. Although numbers of nesting females has increased in recent years on some protected beaches, there is a trend of overall decline. Loss of nesting beaches and egg poaching by humans are prime causes of the population decreases.

The fossil record is absent of specimens of D. coriacea, but D. pseudostracion is known from the Miocene of France. Three extinct Dermochelyid genera (Cosmochelys, Eosphargis, and Psephophorus) are known from the Eocene of Africa, Europe, and North America.

Ernst, C.H., and Barbour, R.W. 1989. Turtles of the World. Smithsonian Inst. Press, Washington, D.C.

Ernst, C.H., Lovich, J.E., and Barbour, R.W. 1994. Turtles of the United States and Canada. Smithsonian Inst. Press, Washington, D.C.

Pough, F.H., Andrews, R.M., Cadle, J.E., Crump, M.L., Savitzky, A.H., and Wells, K.D. 2000. Herpetology, 2nd ed. Prentice Hall, Upper Saddle River, NJ.

Contributors

Keith Pecor (author).

Glossary

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

motile

having the capacity to move from one place to another.