Leatherback turtle

Conservation status

 The leatherback turtle (Dermochelys coriacea) is the largest of all living sea turtles and the fourth largest modern reptile behind three crocodilians. It is the only living species in the genus Dermochelys. It can easily be differentiated from other modern sea turtles by its lack of a bony shell.  Instead, its carapace is covered by skin and oily flesh.
Dermochelys coriacea is the only extant member of the family Dermochelyidae.
Instead of teeth the Leatherback turtle has points on the tomium of its upper lip.
It also has backwards spines in its throat to help it swallow food.
Leatherback turtles can dive to depths as great as 4,200 feet (1,280 metres).

Life history

Like all sea turtles, leatherback turtles start their lives as hatchlings bursting out from the sands of their nesting beaches. Right after they hatch, the baby turtles are already in danger of predation. Many are eaten by birds, crustaceans, other reptiles, and also people before they reach the water. Once they reach the ocean they are generally not seen again until maturity. Very few turtles survive this period to become adults.
It is known that juvenile Dermochelys spend a majority of their particular life stage in more tropical waters than the adults.

Adult Dermochelys are prone to long-distance bouts of migration. Migration in leatherback turtles occurs between the cold waters in which mature leatherbacks cruise in to feed on the abundant masses of jellyfish that occur in those waters, to the tropical and subtropical beaches in the regions where they were hatched from.
In the Atlantic, individual females tagged in French Guiana off the coast of South America have been recaptured on the other side of the ocean in Morocco and Spain.

Mating takes place at sea. Leatherback males never leave the water once they enter it unlike females which crawl onto land to nest. After encountering a female (who possibly exudes a pheromone to signal her reproductive status) a leatherback male uses head movements, nuzzling, biting, or flipper movements to determine her receptiveness.
Females are known to mate every two to three years. However, leatherbacks have been found to be capable of breeding and nesting annually. Fertilization is internal, and multiple males usually mate with a single female.

However, studies have shown that this process of polyandry in sea turtles does not provide the offspring with any special advantages.
While the other species of sea turtles almost-always return to the same beaches they hatched from, female leatherback turtles have been found to be capable of switching to another beach within the same general region of their "home" beach.
Chosen nesting beaches are made of soft sand since their shells and plastrons are softer and easily damaged by hard rocks. Nesting beaches also have shallower approach angles from the sea. This is a source of vulnerability for the turtles because such beaches are easily eroded.

Females excavate a nest above the high-tide line with their flippers.
One female may lay as many as nine clutches in one breeding season. About nine days pass between nesting events. The average clutch size of this particular species is around 110 eggs per nest, 85% of which are viable.
The female carefully back-fills the nest after, disguising it from predators with a scattering of sand.

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