Dermochelys coriacea

Leatherback Turtle

The giant of turtles, the leatherback turtle, also known as the seven-edged turtle, is one of the largest living reptiles and the largest turtle in the world. This species has many extraordinary characteristics, we will mention the most relevant: they are specialists in eating jellyfish, they lay the largest eggs of all turtles, they produce the largest clutches and hatchlings of all turtles, they migrate the longest distances, they grow faster than any other reptile, they are among the most widely distributed vertebrates on the planet and they are the turtles that can dive deeper and longer; their dives can reach up to 1000 m, like whales. Its streamlined carapace creates very little resistance in the water, but its large body size and thick, fatty insulation allow it to control its body temperature in a way that defies the term “cold-blooded reptile.” In fact, it can maintain a constant warm body temperature even in the freezing North Atlantic.

They definitely earn the prize of being one of the rarest vertebrates on the planet.

Leatherback turtles are found in all the world’s oceans, from the Arctic to the tropics and as far south as New Zealand and the Southern Ocean. In the Eastern Pacific it can be found from Alaska to Chile, with nesting areas mainly in Mexico and Central America. In the Mexican Pacific, they can be found on 61 beaches; however, 45% of the total annual nestings are basically concentrated on the following beaches: Mexiquillo, Michoacán; Tierra Colorada, Guerrero; Cahuitán and Barra de la Cruz, Oaxaca; Chacahua and La Tuza beaches, Oaxaca; Zacatosa, Michoacán; Playa Ventura, Guerrero; Todos Santos and Agua Blanca, Baja California Sur.

This species travels great distances from their nesting areas to their feeding and refuge areas. On average it dives to 300 meters, and can be submerged for up to 45 minutes, mainly at night, in search of its food, which consists mainly of jellyfish. According to researchers, only the sperm whale and elephant seal dive deeper and longer than the leatherback.

In each nesting season, each leatherback turtle lays an average of 5 clutches per year, 10 days apart, with an average of 62 eggs per clutch. This turtle takes many years to reach sexual maturity, the estimated time is 14 to 20 years and they do not reproduce every year, presenting a remigration period of 2 to 3 years or more.

Their anatomy and physiology are equally amazing. The carapace of this turtle lacks scutes and is covered by a soft, leathery black skin with white mottling, a leather-like texture unique to all sea turtles. It has 7 longitudinal keels on the carapace and five on the plastron. The length of the carapace can measure up to 1.80 m, and females can weigh up to 500 kg. The head is triangular in shape with two conspicuous maxillary cusps. On the dorsal part, they present a pink spot characteristic of each individual that can be used as individual identification by researchers.

A research taxonomist and anatomist Anders Rhodin studied the skeleton of leatherback turtles for many years and discovered that the ends of their bones contain thick cartilage filled with blood vessels. This characteristic is unique among all other turtles, whose bones have thin cartilage that does not contain blood vessels. The special cartilage of leatherback turtles allows their skeletons to grow rapidly because blood vessels can deliver nutrients to the bones quickly and effectively.

According to the IUCN (International Union for Conservation of Nature) red list, this species is critically endangered and its population is declining. Future population increases will depend on the success of conservation actions that mitigate current and future threats to this species throughout its range, especially in breeding and feeding areas, and that no new threats (e.g., climate change) emerge that could cause population declines.