Hawksbill Sea Turtle

The Hawksbill Sea Turtle, Eretmochelys imbricata was first described by the Swedish botanist, zoologist and physician Carl Linnaeus in 1766. The species name imbricata is Latin for imbricate which corresponds to the overlapping plates, called scutes on the Hawksbill Sea Turtles shell.

_{3D photogrammetry scan of Eretmochelys imbricata specimen. View full size on Pedestal3D}

Identification

The Hawksbill Sea Turtle gets its common name from the distinctive mouth, which resembles a bird’s beak. The shell, or carapace, is covered in large overlapping scutes, which are a distinctive brown/green/amber background with lighter brown streaks throughout. At the edge of the carapace they overlap in such a way as to form a serrated edge. The turtle has an elongated head and flippers which have two visible claws on the end. The flippers and head are covered in large green, brown or yellow scales. The average adult female weighs 50 kg and their carapace (shell) is approximately 80 cm in length.

Habitat

The Hawksbill Sea Turtle lives in tropical coastal waters where they are associated with coral reefs, rocky shoals and mangroves.

Distribution

The Hawksbill Sea Turtle is found in the Indian, Pacific and Atlantic Oceans. It is not found in waters around Sydney, but can be found nesting and foraging along the tropical coasts of Queensland, Northern Territory and Western Australia.

Feeding and diet

Although juveniles are entirely carnivorous, adult Hawksbill Sea Turtles are omnivorous. They feed mostly on sponges; however, they will also eat molluscs, crustaceans, ascidians, marine algae and jellyfish. Hawksbills are highly resilient to their prey and some of the sponges and jellyfish they eat, are toxic to other animals.

Life history cycle

Like all marine turtles, the Hawksbill Sea Turtle spends their entire life at sea, except when nesting females return to lay their eggs as adults. After reaching sexual maturity at about 25-40 years of age Hawksbill turtles return to their natal region (the area that they were born) to breed and lay eggs. At night, they haul themselves up onto the beaches and can lay up to 140 eggs. They may lay one to six clutches in a season and only breed every two to four years. Their lifespan is unknown, but they may take up to 40 years to reach maturity, and possibly live up to 80+ years.

Conservation status

There are seven species of marine turtles in the world and six occur in Australian waters. All species have suffered population declines as a result of pollution, entanglement in fishing nets and egg predation. Populations of the Hawksbill Sea Turtle were also targeted by the tortoiseshell industry, with their scutes being widely used as materials for, as example, buttons, hairpins, jewellery and tourist trinkets. Whole turtles were also commonly prepared as taxidermized wall-hangings, which are still hanging in houses throughout the world. Particularly as this species is associated with coral reefs, it may also be impacted by climate change. As a result of these threats, the Hawksbill Sea Turtle has experienced a population decline of almost 80% in the last 120 years and is listed by the International Union for the Conservation of Nature (IUCN) as Critically Endangered and under the federal Environmental Protection and Biodiversity Conservation Act (EPBC) as Vulnerable. Hawksbill Sea Turtles are also listed on Appendix I under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) which bans all trade in Hawksbill Sea Turtle and tortoiseshell products.

Hawksbill Sea Turtles at the Australian Museum

The Australian Museum holds a number of Hawksbill Sea Turtle specimens that are important for scientific research. The first Hawksbill Sea Turtle to be received by the Australian Museum was in 1886, care of Captain Strachan, a Scottish-born Australian shipmaster and explorer. He was known to have carried out expeditions into Papua New Guinea and may have obtained the specimen there.

There is currently a specimen of the Hawksbill Sea Turtle on display in the Climate Change Gallery, where it highlights the effects on this species.

The Australian Centre for Wildlife Genomics at the Australian Museum is currently collaborating with WWF-Australia and Royal Caribbean International on Surrender Your Shell, to help protect the critically endangered hawksbill turtle. DNA is extracted from surrendered tortoiseshell items and samples added to a database known as ShellBank, which will help to identify hawksbill populations most at risk from the illegal wildlife trade by tracing hawksbill products from sale to where they were poached. For more information about Surrender Your Shell visit, www.wwf.org.au/surrenderyourshell