Hawksbill Turtle.

The hawksbill turtle (Eretmochelys imbricata) is a critically endangered sea turtle belonging to the family Cheloniidae. It is the only species in its genus. The species has a worldwide distribution, with Atlantic and Pacific subspecies. Eretmochelys imbricata imbricata is the Atlantic subspecies, while Eretmochelys imbricata bissa is found in the Indo-Pacific region.

The hawksbill's appearance is similar to that of other marine turtles. It has a generally flattened body shape, a protective carapace, and its flipper-like arms are adapted for swimming in the open ocean. E. imbricata is easily distinguished from other sea turtles by its sharp, curving beak with prominent tomium, and the saw-like appearance of its shell margins. While the turtle lives a part of its life in the open ocean, it is most often encountered in shallow lagoons and coral reefs where it feeds on its chosen prey, sea sponges. Some of the sponges eaten by E. imbricata are known to be highly toxic and lethal when eaten by other organisms. In addition, the sponges that hawksbills eat are usually those with high silica content, making the turtles one of few animals capable of eating siliceous organisms. They also feed on other invertebrates, such as comb jellies and jellyfish.

Because of human fishing practices, Eretmochelys imbricata populations around the world are threatened with extinction and the turtle has been classified as critically endangered by the World Conservation Union. Several countries, such as China and Japan, have valued hunting hawksbill turtles for their flesh, which is considered good eating. Hawksbill turtle shells are the primary source of tortoise shell material, used for decorative purposes. By the Convention on International Trade in Endangered Species, it is illegal to capture and to trade in hawksbill turtles and products derived from them in many nations.

Anatomy and morphology

Eretmochelys imbricata has the typical appearance of a marine turtle. Like the other members of its family, it has a depressed body form and flipper-like limbs adapted for swimming. Adult hawksbill turtles have been known to grow up to a metre (3.3 feet) in length, weighing around 80 kilograms (176 lbs) on average. The heaviest hawksbill ever captured was measured to be 127 kilograms. The turtle's shell, or carapace, has an amber background patterned with an irregular combination of light and dark streaks, with predominantly black and mottled brown colors radiating to the sides.

The hawksbill turtle has several characteristics that distinguish it from other, closely related species. Its elongated, tapered head ends in a beak-like mouth (from which its common name is derived), its beak more sharply pronounced and hooked than other sea turtles. The hawksbill's arms have two visible claws on each flipper.
One of the hawksbill's more-easily distinguished characteristics is the pattern of the thick scutes that make up its carapace. While its carapace has five central scutes and four pairs of lateral scutes like several members of the same family, E. imbricata's posterior scutes overlap in such a way as to give the rear margin of its carapace a serrated look, similar to the edge of a saw or a steak knife. The turtle's carapace itself has been known to reach almost a meter in length.

The sand tracks of hawksbill turtles are asymmetrical, as they crawl on land with an alternating gait. This is opposed to the green sea turtle and the leatherback turtle, which crawl rather symmetrically.
Due to its consumption of venomous cnidarians hawksbill turtle flesh can reach certain levels of toxicity.

Distribution

Hawksbill turtles have a wide range, found predominantly in tropical reefs of the Indian, Pacific and Atlantic oceans. Of all the sea turtle species, E. imbricata is the one most associated with tropical waters. Two major subpopulations are acknowledged to exist, the Atlantic and Indo-Pacific subpopulations.