Leatherback Sea Turtle (Dermochelys coriacea)

Leatherbacks are the largest turtles on Earth, growing up to seven feet (two meters) long and exceeding 2,000 pounds (900 kilograms). These reptilian relics are the only remaining representatives of a family of turtles that traces its evolutionary roots back more than 100 million years. Once prevalent in every ocean except the Arctic and Antarctic, the leatherback population is rapidly declining in many parts of the world.

While all other sea turtles have hard, bony shells, the inky-blue carapace of the leatherback is somewhat flexible and almost rubbery to the touch. Ridges along the carapace help give it a more hydrodynamic structure. Leatherbacks can dive to depths of 4,200 feet (1,280 meters)—deeper than any other turtle—and can stay down for up to 85 minutes.

Leatherbacks have the widest global distribution of all reptile species, and possibly of any vertebrate. They can be found in the tropic and temperate waters of the Atlantic, Pacific, and Indian Oceans,

Olive Ridley Sea Turtle (Lepidochelys olivacea)

Olive ridleys get their name from the coloring of their heart-shaped shell, which starts out gray but becomes olive green once the turtles are adults. They have one to two visible claws on each of their paddle-like flippers.

The olive ridley turtle is named for the generally greenish color of its skin and shell, or carapace. It is closely related to the Kemp’s ridley, with the primary distinction being that olive ridleys are found only in warmer waters, including the southern Atlantic, Pacific and Indian Oceans.

Olive and Kemp’s ridleys are the smallest of the sea turtles, weighing up to 100 pounds (45 kilograms) and reaching only about 2 feet (65 centimeters) in shell length. The olive ridley has a slightly smaller head and smaller shell than the Kemp’s.

These turtles are solitary, preferring the open ocean. They migrate hundreds or even thousands of miles every year, and come together as a group only once a year for the arribada,