The leatherback sea turtle is the largest marine turtle species. They can weigh up to 800kg (1,770lbs) and measure between 1.3 and 1.8m (4.25 and 6ft) long. Leatherback sea turtles may exceed with this with the largest recorded individual measuring 3.05m (10ft) long and weighing 916kg (2,019lbs).
Their name comes from the leathery appearance of their shell which covers their back. Unlike other turtles their shell is flexible and rubbery. Running from the head to the back are seven ridges along the shell. These ridges help to make them more hydrodynamic. The shell is colored dark grey or black on their back which is patterned with white or pale spots. On the underside the shell is colored white or black.
On the throat and sides of the neck the skin is colored white, cream or pink with blotches of brown and black.
The feet of the leatherback sea turtle have formed in to flippers which do not have a claw at their end. These large paddle shaped flippers help to push them through the water.
They have a large head which is located at the end of a short, thick neck.
The leatherback sea turtle feeds almost exclusively on jellyfish and other soft, gelatinous animals such as squid.
To help catch their food they have spikes at the back of their throat which help to stop their prey from escaping.
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Leatherback sea turtles are found in the world’s oceans. Males spend their whole life at sea while females only come to land for a few hours each year to lay their eggs.
Nesting locations can be found on tropical beaches along the coastline of all continents except Antarctica.
They have the largest range of any reptile and potentially the largest range of any vertebrate species.
They can be found in most of the warm tropical, subtropical and temperate areas of the ocean worldwide only avoiding the cold areas of the Arctic and Antarctic oceans.
Mating takes place at sea. Males return to the same beach each season as long as they are having success there. The males have many mates in a breeding season.
The breeding season is variable across their range. In the US they lay eggs from March to July. In Australia this occurs during December and January.
Females come ashore at night and dig a hole in the sand. Most return to the same beach where they born to lay eggs. In to this hole they will deposit 80-85 eggs which are spherical and white. Once the eggs are deposited the female fills the hole leaving a large area of disturbed sand which makes it harder for predators to find the nest site. A female leatherback will lay many times during the breeding season.
A female will typically nest once every 2 or 3 years.
Incubation lasts 65 days. The gender of the hatchlings is determined by the temperature at which they incubate. Higher temperatures produce females and cooler temperatures produce males. An intermediate temperature will produce a mixture of both.
The young can break themselves out of the egg using a special tooth. They are independent from birth.
Hatchlings have five ridges running along their shell.
There age at sexual maturity has not been adequately determined. Estimates range between 9 and 29 years.
While a large number of young are produced by each female only one in every 1,000 hatchlings will make It to adulthood.
Each year they undertake long migrations between the breeding and feeding sites. They conduct the longest migration of any sea turtle.
Leatherback sea turtles can dive to great depths. The deepest recorded dive was almost 1,219m (4,000ft). They may remain underwater for over an hour.
Unlike other reptiles the leatherback sea turtle has a limited ability to warm its own body. This is achieved through their large size, a thick layer of fat and changes in their blood flow.
Predators and Threats
Their eggs face a number of predators including crabs, monitor lizards, birds, raccoons, coatis, genets, mongooses and pigs. After hatching the young must make their way to the sea while avoiding birds such as raptors and gulls along with many of the egg predators.
Adults have relatively few predators. On land they can be attacked by jaguars and at sea they are threatened by killer whales and sharks.
Humans threaten their population through by catch in fisheries, habitat destruction, vehicle strikes and marine pollutants. A major pollutant is plastic which can be mistaken for jellyfish. Some individuals have been found with as much as 5kg (11lbs) of plastic in their stomach. They are also hunted both as eggs and as adults to collect their meat and shells.
Due to their gender being determined by the temperature at incubation they could be affected by climate change which would lead to a population skew towards females in the population.
Leatherback sea turtles existed at the same time as the dinosaurs and have not changed since.
The deepest recorded dive of a leatherback sea turtle is believed to be the deepest dive of any reptile.
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