The Hawksbill Sea Turtle | Anatomy
The Hawksbill sea turtle or Eretmochelys imbricata is currently classified as a Critically Endangered species by the International Union for the Conservation of Nature and Natural Resources. This means that the Hawksbill faces great risk of extinction in the near future. Although it is protected by law under The Convention on International Trade in Endangered Species, international trade in the shells of the Hawksbill sea turtle as well as incessant use of its eggs and meat remain undeterred in many countries and pose a formidable threat to the survival of this one-of-a-kind species. Human fishing is another threat to Hawksbill turtles.
The Hawksbill sea turtle belongs to the family Cheloniidae and is the only species in its genus. It is one of the smaller species of sea turtles. The small to medium-sized Hawksbill turtle can be found worldwide; mostly in the Atlantic and Pacific oceans. It is described as the most tropical of all marine turtles. The Hawksbill sea turtle is usually found in waters no deeper than 65 feet. Its favoured habitats include shallow coastal areas, continental shelf regions, islands, coral reefs, lagoons, oceanic islands, rocky areas, shoals, and narrow creeks and passes. Though the Hawksbill sea turtle lives some part of its life in the ocean, most of its time is spent in coral reefs and shallow lagoons.
The Hawksbill sea turtle can weigh up to 180 lbs. and can grow up to three feet in length. In 1952, a man named Archie Carr recorded an all-time high of 127 kilograms for a Hawksbill turtle. Hatchlings range in weight from 13.5 to 19.5 grams and average about 42 millimetres in shell length.
Because of their paddle-like flippers and smooth shells, the Hawksbill can glide through the water with speeds that go up to as fast as 24 kilometres per hour. Records have shown that these long-distance travellers have reached lengths of up to 4,828 kilometres.
Although similar in physical appearance to other marine turtles, a number of characteristics distinguish it nonetheless. These include:
• Two visible claws on each flipper
• Two pairs of pre-frontal scales
• Four pairs of costal scutes on its shell
• Thick scutes on the shell overlapping the posterior (hence its name)
• An irregular or asymmetrical gait when on land, unlike its green sea turtle and leatherback counterparts
• A mouth designed like a hawk’s beak (another reason for its name)
In baby Hawksbills, the shell is shaped like a heart and can sub-ovate or elongate as it reaches maturity. The colour of the Hawksbill’s belly can be described as light yellow-cream to amber with black spots. Hawksbill sea turtles found in the Atlantic region commonly have bellies that are an unusual shade of clear yellow with no or very little dark pigmentation. The soft skin found on its abdomen area is yellow or cream and at times, orange with a shade of pink in older Hawksbill turtles.
The head of the Hawksbill sea turtle is elongated, relatively small, and tapers sharply to a point. The scales of the forelimbs and head are either black or dark brown with yellow borders that are sharply defined. The mouth of the Hawksbill turtle is more hooked and sharply pronounced than other marine turtles. It is the narrow shape of the Hawksbill’s jaws and head that permit it to obtain food from crevices found in coral reefs. The diet of a Hawksbill sea turtle normally includes coelenterates, shrimp, fish, anemones, echinoderms, bryozoans, sponges and squid.
Male Hawksbill turtles are described as having thicker tails, brighter pigmentations, longer claws, and a concave belly.
With the exception of extremely old turtles, the rear and side parts of the shell are sharply serrated in adult and juvenile Hawksbill sea turtles alike. These parts are likened to the edge of a steak knife or a saw. Juvenile Hawksbills are either very dark brown or black with yellow or light brown colourings on the edge of their limbs and shells. Hawksbill sea turtles are the only marine turtles in the world that have four pairs of costal scutes on their shells as well as two pairs of pre-frontal scales.
The shell of the Hawksbill can slightly change colour at times, contingent on the temperature of the water it finds itself in. Its shell is very beautifully marked. Splashes of reddish-brown, yellow, orange and amber markings found on its shell have made it an extremely popular target for commercial hunters of tortoiseshell. This distinction has been a main factor in the ‘endangered’ status of the Hawksbill turtle. It is the epidermal scutes that cover the bones of the shell that go into commercial use. The unique shell of the Hawksbill turtle is used by hunters to make jewellery, hair ornaments, furniture, souvenirs as well as other decorative items. Because of the proclivity of the Hawksbill sea turtle to feed on venomous cnidarians, the consumption of its flesh can be toxic to human beings.
Unlike regular turtles, it is not possible for sea turtles to hide their heads in their shells. However, Hawksbills are protected from predators by the thick, scaly skin found on their necks and heads, their shells, and their size.
In certain parts of the world, Hawksbill sea turtles are considered a delicacy. Dating as far back as the fifth century B.C., records have shown that sea turtles, including Hawksbills, were being eaten as delicacies in China. It is generally agreed upon that their slow reproductive rates, slow maturity and growth and long life spans are the reasons behind why Hawksbill sea turtles are considered critically endangered species today. Whether accidental or deliberate, human beings are the culprits behind many a death of a Hawksbill sea turtle.
In 2006, The Convention on International Trade in Endangered Species declared the importing and exporting of turtle products and killing, capturing and harassment of Hawksbill sea turtles as illegal activities. The past few years have also seen local government units and non-profit organizations showing increased involvement in conservation efforts of Hawksbill sea turtles. Ultimately, it is up to us to decide whether or not this beautiful creature lives or dies.