Leatherback Sea Turtle - Anatomy and Physiology

Anatomy and Physiology

Leatherback turtles have the most hydrodynamic body design of any sea turtle, with a large, teardrop-shaped body. A large pair of front flippers power the turtles through the water. Like other sea turtles, the leatherback has flattened forelimbs adapted for swimming in the open ocean. Claws are absent from both pairs of flippers. The leatherback's flippers are the largest in proportion to its body among extant sea turtles. Leatherback's front flippers can grow up to 2.7 metres (8.9 ft) in large specimens, the largest flippers (even in comparison to its body) of any sea turtle.

The leatherback has several characteristics that distinguish it from other sea turtles. Its most notable feature is the lack of a bony carapace. Instead of scutes, it has thick, leathery skin with embedded minuscule osteoderms. Seven distinct ridges rise from the carapace, crossing from the anterior to posterior margin of the turtle's back. Leatherbacks are unique among reptiles in that their scales lack β-keratin. The entire turtle's dorsal surface is colored dark grey to black, with a scattering of white blotches and spots. Demonstrating countershading, the turtle's underside is lightly colored.

Instead of teeth, the leatherback turtle has points on the tomium of its upper lip, with backwards spines in its throat to help it swallow food.

Dermochelys coriacea adults average 1–1.75 m (3.3–5.74 ft) in carapace length, 1.83–2.2 m (6.0–7.2 ft) in total length and weigh 250 to 700 kg (550 to 1,500 lb). In the Caribbean, the mean size of adults was reported at 384 kg (850 lb) in weight and 1.55 m (5.1 ft) along the curve of the carapace. The largest ever found, however, was over 3 metres (9.8 ft) from head to tail, including a carapace length of over 2.2 metres (7.2 ft), and weighed 916 kilograms (2,020 lb). That specimen was found on a beach on the west coast of Wales. Remarkably, the leatherback turtle is scarcely larger than any other sea turtle upon hatching, as they average 61.3 mm (2.41 in) in carapace length and weigh around 46 g (1.6 oz) when freshly hatched.

Dermochelys coriacea exhibits a suite of anatomical characteristics believed to be associated with a life in cold waters, including an extensive covering of brown adipose tissue, temperature independent swimming muscles, counter-current heat exchangers between the large front flippers and the core body, as well as an extensive network of counter-current heat exchangers surrounding the trachea.