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The olive ridley, or lepidochelys olivacea, is the smallest sea turtle in the world. At maturity it averages 27.5 inches (70 centimeters) long and usually weighs less than 100 pounds (45 kilograms). It is the most abundant sea turtle, inhabiting tropical locales in the Indian, Pacific, and south Atlantic oceans. The olive ridley has an olive-colored carapace, or upper shell. It was named after H.N. Ridley, a Malyasian botanist and scholar who was well-known around the turn of the 20th century.
Olive ridleys are omnivorous, and primarily eat crustaceans, mollusks, jellyfish, sea urchins and rock lobsters. Their diet also includes crabs, shrimp, snails, fish, and fish eggs. When their usual sources of food aren’t available, they will eat algae.
This small marine turtle has an unusual nesting habit called an arribada. During an arribada, hundreds or thousands of turtles gather offshore. At a synchronized time, they crawl on land en masse to lay their eggs.
The arribada is unique to olive ridley turtles, and no one knows what sets it in motion. Scientists have proposed several theories to explain it. Some believe the arribada may be triggered by pheromones being emitted by the females, and others conjecture that offshore winds are responsible. Lunar cycles have also been suggested as a possible cause.
Adult females lay eggs once or twice every year. Their clutches contain an average of 110 eggs. These eggs have an incubation period of approximately 52 to 58 days.
Egg nests are vulnerable to a host of predators. Opossums, raccoons, snakes, ghost crabs, and feral dogs enjoy feasting on the unhatched eggs. As the hatchlings crawl across the beaches from their nests to the water, they become food for vultures, coyotes, raccoons, crabs, and snakes. Once in the water, the olive ridley becomes prey to crocodiles, sharks, and fish.
The olive ridley has been listed as an endangered species. Humans are considered their worst predator. Adult olive ridleys are slaughtered for their meat and hides. People also collect their eggs in numbers too large to sustain the turtles’ population.
Olive ridleys also become incidental catch in large fishery operations and suffer mortal wounds from colliding with boats. Pollution, coastal development, and erosion have decreased their nesting sites and have had an adverse impact on their foraging areas. Although there are sanctions in many countries against collecting the eggs and harvesting adult olive ridleys, the challenges of global enforcement have rendered them largely ineffective.