The hawksbill sea turtle (Eretmochelys imbricata) is a Critically Endangered sea Turtle belonging to the family Cheloniidae. It is the only extant Speciess in the Genus Eretmochelys. The species has a worldwide distribution.
The hawksbill's appearance is similar to that of other marine 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.
Hawksbill is the smallest of the Sea turtles and its slender profile gives it a streamlined, agile appearance.
They are the fastest of all of the sea turtles.
Its top shell or carapace is the classic tortoiseshell with a rich reddish brown or dark brown mottling. Their shell is architecturally different from any other turtle’s.
The scutes of its upper shell overlap, much like a shingled roof. Its bottom shell is golden.
Adult hawksbill sea turtles are primarily found in tropical coral reefs. They are usually seen resting in caves and ledges in and around these reefs throughout the day. As a highly migratory species, they inhabit a wide range of habitats, from the open ocean to lagoons and even mangrove swamps in estuaries. Little is known about the habitat preferences of early life-stage E. imbricata; like other young sea turtles, they are assumed to be completely pelagic, remaining at sea until they mature.
While they are omnivorous, Sea sponges and sea grasses are their principal food; they constitute 70–95% of the turtles' diets. However, like many spongivores, they feed only on select species, ignoring many others. Most of the turtles feed primarily on the orders Astrophorida, Spirophorida, and Hadromerida in the class Demospongiae. Aside from sponges, hawksbills feed on algae, cnidarians, comb jellies and other jelyy fish, and Sea anemones.They also feed on the dangerous jellyfish-like Hydrozoans, the Portuguese man of war(Physalia physalis). Hawksbills close their unprotected eyes when they feed on these cnidarians. The man of war's stinging cells cannot penetrate the turtles' armored heads.
Hawksbills are highly resilient and resistant to their prey. Some of the sponges they eat, such as Aaaptos aapstos, chondrilla nucula, tethya Actinia,spheciosspongia vesparium, and suberites domuncula, are highly (often lethally) toxic to other organisms. In addition, hawksbills choose sponge species with significant numbers of siliceous spicules, such as Ancornia, geodia(G.gibberosa),ecionemia and placospongia.
The 6 month nesting season of the hawksbill is longer than that of other sea turtles.
Nesting behaviour follows a general sequence of that of other species of sea turtles: emergence from the sea, site selection, site clearing and pit construction, egg chamber construction, egg laying, filling in the egg chamber, disguising the nest site, and returning to sea. The entire process takes about 1 to 3 hours.
Hawksbills nest on average 4.5 times a season and intervals of about 14 days. Hawksbills have a strong site fidelity to specific nesting beach areas and are capable of returning to the same place season after season. Clutch size is correlated to female carapace length. Eggs are about 40 mm in diameter and take about 60 days to hatch. Sex determination is likely temperature-dependent as in other sea turtles and many reptiles, but data is limited.
Hawksbills mate biannually in secluded lagoons off their nesting beaches in remote islands throughout their range. Indian Ocean populations, mate from September to February.After mating, females drag their heavy bodies high onto the beach during the night. They clear an area of debris and dig a nesting hole using their rear flippers, then lay clutches of eggs and cover them with sand. Nests of E. imbricata normally contain around 140 eggs. After the hours-long process, the female returns to the sea.
Consensus has determined sea turtles, including E. imbricata to be, at the very least, threatened species because of their slow growth and maturity, and slow reproductive rates. Many adult turtles have been killed by humans, both accidentally and deliberately. Their existence is threatened due to pollution and loss of nesting areas because of coastal development. Biologists estimate that the hawksbill population has declined 80 percent in the past hundred years. Human and animal encroachment threatens nesting sites, and small mammals dig up the eggs to eat.
The species (along with the entire family Cheloniidae) has been listed on Appendix I of the Convention on International Trade In Endangered Species. It is illegal to import or export turtle products, or to kill, capture, or harass hawksbill sea turtles.
Throughout the world, hawksbill sea turtles are taken by humans, though it is illegal to hunt them in many countries. In some parts of the world, hawksbill sea turtles are eaten as a delicacy. Many cultures also use turtles' shells for decoration.