Leatherback Turtle (Dermochelys coriacea)
What does it look like?
The leatherback turtle gets its name from its unusual shell. Unlike other marine turtles, which have a carapace (upper shell) made of flattened bones called scutes, the leatherback’s tapering carapace has a lot of small bones embedded in a tough, rubbery skin, which has seven ridges running all the way down to its pointy posterior. The turtle is black with light-coloured spots, and a pale pink splotch on the top of its head (this is individual, like a fingerprint, and some researchers use it to tell individuals apart!). Hatchlings are black, with white markings on the carapace ridges and plastron (lower shell).
The largest of all turtles, the leatherback can grow to over 1.75 m long and weigh over 500 kg! But despite its somewhat fearsome appearance, this turtle has no teeth. Its mouth instead has special notches used to grip soft prey, such as jellyfish and other squashy invertebrates.
Where does it live?
The leatherback turtle is found from the Arctic Circle to south of New Zealand – the widest distribution of any marine turtle. It forages along coastlines and in the open sea, with adults diving more than 1100 m deep! The leatherback can survive colder waters because in some ways it is more like a seal than a ‘cold-blooded’ reptile. Unlike other reptiles, which derive their body heat from their external environment, the leatherback can keep its body temperature up to 18° C higher than the water temperature! Its huge body mass, muscle activity and an insulating layer of fat help keep this amazing animal nice and cosy. Although the leatherback is a rare visitor to Shark Bay’s warm, shallow seas it has been spotted, easily distinguishable by its distinctive body shape.
How does it breed?
Although leatherback turtles breed in the tropics, there are no major breeding colonies in Australia. A few turtles nest at scattered sites in the Northern Territory and northern Queensland, but most turtles living in Australian waters migrate to breed in neighbouring countries, such as Indonesia, Malaysia and Papua New Guinea. There has not been a nesting record of a leatherback turtle in Queensland for over 10 years.
The few females that nest in Australia do so every 2–4 years, in December and January. They lay clutches of about 90 eggs, buried up to 1 m deep! As with other marine turtle species, the sex of the hatchling is determined by incubation temperature, with warmer beaches producing mostly female hatchlings. In Australia, the tiny hatchlings emerge in February and March. Measuring just 6 cm long and weighing 47 g, they immediately begin their perilous journey to the sea.
Any threats to its survival?
The leatherback turtle is listed as critically endangered
which means the species is on the brink of extinction. Crabs, seabirds and fish make a quick snack of hatchlings, but the main threat to the leatherback’s survival is human activities. Like other marine turtle species, it is drowned in trawl nets, tangled in fishing and lobster pot lines, and struck by boats. Leatherbacks are also choked or strangled when they mistake plastic bags and other rubbish for their favourite food, jellyfish. In some countries their eggs are harvested. Since the leatherback grows slowly and takes decades to reach maturity, more eggs are being collected than being hatched – and the odds of a hatchling surviving to adulthood are extremely slim.
How do you identify marine turtles?
to go to our Shark Bay
marine turtle identification guide!
to download a printable PDF of this fact sheet.