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Hawksbill Turtle

(Eretmochelys imbricata )

Short Description

The Hawksbill Turtle is an increasingly rare sea turtle belonging to the family Cheloniidae. Because of human fishing practices, 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 a delicacy.

Hawksbill turtle shells are the primary source of tortoise shell material, used for decorative purposes. By the Convention on International Trade in Endangered Species (CITES) , it is illegal in many nations to capture and to trade in hawksbill turtles and products derived from them.

Long Description

Size
Adult Hawksbill Turtles have been known to grow up to a meter (3.3 feet) in length, weighing around 80 kilograms (175 lb) on average. The heaviest hawksbill ever captured was measured to be 127 kilograms (280 lb).

Identification
The Hawksbill's appearance is similar to that of other marine turtles. It has a generally flattened body shape, a protective carapace, and flipper-like arms, adapted for swimming in the open ocean. The Hawksbill is easily distinguished from other sea turtles by its sharp, curving beak with prominent tomium, and the saw-like appearance of its shell margins.

The shells of the Hawksbill turtles slightly change colors, depending on the temperature of the water. The 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.

Its beak is more sharply pronounced and hooked than other sea turtles, and 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, 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.

Diet
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 primary prey, sea sponges. Some of the sponges eaten by it 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. Due to its consumption of venomous cnidarians, hawksbill turtle flesh can reach certain levels of toxicity.

Social Groups and Activity
Hawksbill Turtles are believed to live from thirty to fifty years in the wild. Like other sea turtles, hawksbill turtles are solitary for most of their lives, grouping together only to mate. They are now known to be highly migratory, and because of their tough carapaces, they have no major predators, as few creatures are capable of biting through the protective shell.

Throughout the world, hawksbill turtles are taken by humans even though it is illegal to hunt them in many countries – their flesh is a delicacy in China and the shell is highly sought after for decorative purposes. They are considered to be a threatened species because of their long lifespans, slow growth and maturity, and slow reproductive rates. Their nesting spots on popular tourist beaches are also subject to degradation. They are now considered to be critically endangered.

Reproduction
Hawksbills are known to mate biyearly in secluded lagoons in remote islands throughout their range. Mating season for Atlantic hawksbills usually takes place from April to November. For Indian Ocean populations such as the Seychelles hawksbill population, the mating season is from September to February. As with other sea turtles, hawksbills mate in shallow lagoons off the shores of their prospective nesting beaches. After mating, the females drag their heavy bodies high onto the beach during the night. They will then clear out an area and dig a nesting hole using their rear flippers. The female then lays a clutch of eggs in the nest and then covers them with sand. Caribbean and Florida nests of E. imbricata normally contain around 140 eggs. After the several-hour-long process, the female then returns to the sea. This is the only time when hawksbill turtles are known to leave the ocean.

The baby turtles, usually weighing less than two dozen grams, hatch during the night after around two months. These newly emergent hatchlings are dark-colored, with heart-shaped carapaces measuring around 2.5 centimeters (1 in) long. They instinctually head for the sea, attracted by the reflection of the moon on the water (a mechanism which can be disrupted by artificial light sources such as street lamps and lights). While they emerge under the cover of darkness, baby turtles that do not reach the water by daybreak are preyed upon by predators such as shorebirds and shore crabs.

Distribution

Adult Hawksbill 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 have also been encountered in a wide range

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, Eretmochelys imbricata imbricata is the Atlantic subspecies, while Eretmochelys imbricata bissa is found in the Indo-Pacific region.

E. imbricata (Atlantic) populations can be seen as far west as the Gulf of Mexico and as far southeast as the Cape of Good Hope in South Africa. They are known from the Brazilian coast (specifically Bahia) through southern Florida and the waters off Virginia. The species' range extends as far north as Long Island Sound and Massachusetts in the west Atlantic and the frigid waters of the English Channel in the east - the species' northernmost sighting to date.

In the Caribbean, they have been seen nesting on beaches of Antigua and Barbuda and in the vicinity of Tortuguero in Costa Rica. The waters off Cuba and around Mona Island near Puerto Rico are known feeding grounds.

The Indo-Pacific population is widespread. In the Indian Ocean, hawksbills are a common sight all along the east coast of Africa, including the seas surrounding Madagascar and nearby island groups, and all the way along the southern Asian coast, including the Persian Gulf, the Red Sea, and the coasts of the Indian subcontinent and Southeast Asia. They are present across the Indonesian archipelago and northern Australia.

The Pacific range of E. imbricata is limited to the ocean's tropical and subtropical regions. In the west, it extends from the southwestern tips of the Korean peninsula and the Japanese archipelago down to northern New Zealand. In the east Pacific, hawksbills are known from the Baja peninsula in Mexico south along the coast to northern Chile.

Distribution Map

Hawksbill Turtle  Distribution Map

Various

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