The hawksbill sea turtle (Eretmochelys imbricata) is a critically endangered sea turtle belonging to the family Cheloniidae. It is the only extant species in the genus Eretmochelys. The species has a global distribution that is largely limited to tropical and subtropical marine and estuary ecosystems. The appearance of the hawksbill is similar to that of other sea turtles. In general, it has a flattened body shape, a protective carapace, and flipper-like limbs, 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. Hawksbill shells slightly change colors, depending on water temperature. While this turtle lives part of its life in the open ocean, it spends more time in shallow lagoons and coral reefs. The World Conservation Union classifies E. imbricata as critically endangered, primarily as a result of human fishing practices. Hawksbill shells were the primary source of tortoiseshell material used for decorative purposes. The Convention on International Trade in Endangered Species regulates the international trade of hawksbill sea turtles and products derived from them.
Taxonomy
Linnaeus described the hawksbill sea turtle as Testudo imbricata in 1766, in the 12th edition of his Systema Naturae. In 1843, Austrian zoologist Leopold Fitzinger moved it into the genus Eretmochelys. In 1857, the species was temporarily misdescribed as Eretmochelys imbricata squamata. Neither the IUCN nor the United States Endangered Species Act assessment processes recognize any formal subspecies, but instead recognize one globally distributed species with populations, subpopulations, or regional management units. Fitzinger derived the genus name Eretmochelys from the Ancient Greek roots eretmo and chelys, corresponding to "oar" and "turtle", respectively, in reference to the turtles' oar-like front flippers. The species name imbricata is Latin, corresponding to the English term imbricate, in reference to the turtles' shingle-like, overlapping carapace scutes.
Description Adult hawksbill sea turtles typically grow to 1 m (3 ft) in length, weighing around 80 kg (180 lb) on average. The heaviest hawksbill ever captured weighed 127 kg (280 lb). 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. Several characteristics of the hawksbill sea turtle distinguish it from other sea turtle species. Its elongated, tapered head ends in a beak-like mouth (from which its common name is derived), and its beak is more sharply pronounced and hooked than others. The hawksbill's forelimbs have two visible claws on each flipper. A readily distinguished characteristic of the hawksbill is the pattern of thick scutes that make up its carapace. While its carapace has five central scutes and four pairs of lateral scutes like several members of its 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 can reach almost 1 m (3 ft) in length. The hawksbill appears to frequently employ its sturdy shell to insert its body into tight spaces in reefs. Crawling with an alternating gait, hawksbill tracks left in the sand are asymmetrical. In contrast, the green sea turtle and the leatherback turtle have a more symmetrical gait. Due to its consumption of venomous cnidarians, hawksbill sea turtle flesh can become toxic. The hawksbill is biofluorescent and is the first reptile recorded with this characteristic. If the effect is due to the turtle's diet, which includes biofluorescent organisms like the hard coral Physogyra lichtensteini, is unknown. Males have more intense pigmentation than females, and a behavioral role of these differences is speculated.
Distribution Hawksbill sea 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 warm, tropical waters. Two significant subpopulations are known, in the Atlantic and Indo-Pacific.
Atlantic subpopulation
In the Atlantic, hawksbill populations range as far west as the Gulf of Mexico and as far southeast as the Cape of Good Hope in South Africa. They live off the Brazilian coast (specifically Bahia, Fernando de Noronha). Along the East Coast of the United States, hawksbill sea turtles range from Virginia to Florida. In Florida, according to the Florida Fish and Wildlife Conservation Commission, hawksbills are found primarily on reefs in the Florida Keys and along the southeastern Atlantic coast. Several major nesting sites are found in coastal Palm Beach, Broward, and Dade Counties. The Florida Hawksbill Project is a comprehensive research and conservation program to study and protect the region's hawksbill sea turtles and the habitats in which they live. Within the scope of this project, numerous studies have been undertaken to characterize the hawksbill aggregations found in southeast Florida waters, and educational programs have been developed to engage the local dive community in the protection of hawksbill sea turtles and coral reef habitats. This program is hosted by the National Save the Sea Turtle Foundation, located in Fort Lauderdale, Florida. Throughout their global range, hawksbill turtles are known to closely associate with coral reef habitats, mostly due to their preference for eating sponges and corals. Due to the large extent of Florida's barrier reefs (about 350 linear miles), the Hawksbill Project focuses on representative sites in the northern, central, and southern sections of the Southeast Florida Reef Tract. The barrier reefs of northern Palm Beach County, the patch reefs of the northern Keys, and the finger reefs of Key West are the primary locations for their sampling efforts In the Caribbean, the main nesting beaches are in the Lesser Antilles, Barbados, Guadeloupe, Tortuguero in Costa Rica, and the Yucatan. They feed in the waters off Cuba and around Mona Island near Puerto Rico, among other places.
Indo-Pacific subpopulation
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