Known as: Olive Ridley Sea Turtle, Pacific ridley sea turtle
Estimated numbers left in wild: 800,000 nesting females.
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Description of the Oliver Ridley Sea Turtle
The olive ridley sea turtle is one of the smallest of the sea turtles, measuring only 60 to 70 centimeters and weighing in at about 45 kilograms.
The colour of this turtle’s shell and skin are what give the olive ridley its name, and the color can range from a dull greyish green to a more obvious olive green. The under the shell, the plastron, is a cream colour, but algal growth can sometimes result in it developing a reddish hue. The head of the turtle is medium-sized and the flippers, which are used for swimming, each have 2 claws (remnants of terrestrial feet).
These turtles are omnivorous and will eat fish, crabs, tunicates, shrimp, algae, and lobsters. They will dive down to depths of 150 meters to search for bottom-dwelling food. Olive ridley sea turtles will migrate long distances between feeding grounds and nesting sites.
One of the characteristics of the olive ridley is that it will nest in enormous numbers at certain locations, and the turtles begin congregating near the nesting beaches 2 months before they will actually come ashore. It is not unknown for thousands of female olive ridleys to come ashore en masse to lay their eggs. There are often so many of the turtles trying to deposit their eggs that latecomers will inadvertently dig up previously laid eggs. These mass egg-laying episodes are called ‘arribadas’.
The beaches of Odisha, India, once saw over half a million olive ridleys come ashore over seven days to lay eggs. Each female can lay 100 eggs or more, and many of them nest 3 times a year. The eggs will take approximately 2 months to hatch, and as the baby turtle emerges from the sand and head for the ocean they run a gauntlet of predators: gulls, raccoons, crabs, and pigs. Interestingly, the temperature at which the eggs are incubated determines the sex ratio of the turtles – a 1:1 ratio occurs when the temperature is 29 – 30 C, while a higher temperature than this will produce only females and a lower one only males.
Location: Olive ridley sea turtles have a worldwide distribution, inhabiting tropical and subtropical waters through the Atlantic, Pacific, and Indian Oceans. Nesting beaches occur on the west coast of India, in Central and South America, on the coast of Africa, and at 2 sites in Australia.
Although the olive ridley sea turtle still seems to have a robust population, this turtle still faces many threats to its continued wellbeing. In many locations, the turtles are still hunted for food, especially when they come ashore to nest, and eggs are also taken for food (especially in Mexico).
Turtles can become entangled in fishing nets, and off the coast of California, they are sometimes sucked up into the water cooling ducts of power plants.
The olive ridley sea turtle is listed in CITES as vulnerable and this has helped to curb trade in the turtles’ skins and shells. Efforts to enforce conservation on a worldwide scale, as suggested by the International Union for Conservation of Nature and Natural Resources, have also helped to protect the turtles. Shrimp trawling boats must now be fitted with turtle excluders, reducing accidental mortality from commercial shrimping.
Oceana is the largest international organization focused only on ocean conservation, protecting marine ecosystems and endangered species such as the Olive Ridley Sea Turtle.