Sea Turtles & Reptiles
Olive Ridley Turtle
Worldwide in tropical and subtropical waters
Class Reptilia (reptiles), Order Testudines (turtles), Family Cheloniidae (hard-shelled sea turtles)
The olive ridley turtle is the most abundant sea turtle species in the world and is known for its mass nesting aggregations called arribadas (meaning “arrival” in Spanish). Arribadas occur so that there are safety in numbers. More hatchlings survive when they enter the sea with hundreds of others, as opposed to hatchlings born from a solitary nester. Olive ridley turtles are also one of the smallest sea turtle species at only 2 to 2.5 feet (0.6 to 0.7 m) long and 80 to 110 pounds (36 to 50 kg). They are named for the olive coloration of their heart-shaped shells.
Olive ridley turtles live globally in the coastal waters of at least 80 countries. Generally, olive ridley turtles are not known to move between or among ocean basins. They may migrate between neritic and oceanic zones near their nesting beaches. Olive ridley turtles are the most abundant sea turtle species largely due to their mass nesting aggregations in Mexico, India, Nicaragua and Costa Rica. Upward of 521,000 nests are laid every year on Indian beaches alone.
Olive ridley turtles mate in the ocean. Females can store sperm throughout the breeding season, enabling them to produce one to three clutches of eggs at intervals. Like all sea turtles, females nest on the beach where they were born. While some female olive ridley turtles are solitary nesters, many are synchronized nesters, emerging from the water during the same 28-day period to nest with hundreds or thousands of other olive ridleys. Females lay 50 to 200 eggs in each nest and return to the ocean shortly after.
Eggs incubate for 50 to 60 days before they hatch. The warmer the eggs are during incubation, the more females will be produced. Likewise, if the nest is colder, there will be more males. As the olive ridley hatchlings make their way to the ocean, they have a low chance of survival, facing threats from predators such as seabirds, crabs and fish. Little is known about the diet of juvenile olive ridley turtles, but adults are omnivores and forage on a variety of prey. They are known to eat jellyfish, shrimp, crabs, tunicates and sometimes algae.
Olive ridley turtles are believed to be long-lived much like other sea turtles, but their full age has yet to be determined. Because they live long, olive ridley turtles do not reach sexual maturity until 13 years old, making this species vulnerable to natural population declines. Olive ridley turtles also face a number of unnatural threats from human activities that have made this species endangered in Mexico and threatened with extinction everywhere else.
Olive ridley turtles are caught as bycatch in commercial fisheries such as trawling, gillnets and longlines. They are also susceptible to entanglement from ghost gear (fishing nets discarded in the ocean), and face suffocation and starvation from marine debris. Moreover, habitat and nesting site degradation from coastal developments and climate change threaten the survival of future olive ridley populations. Lastly, illegal egg poaching, turtle harvesting and nest destruction by humans is so rampant that only 1 to 8 percent of eggs laid during arribadas hatch. All threats considered, olive ridley turtles experienced a population decrease of 28 to 32 percent from 1988 to 2008. Without better enforcement of poaching laws and the use of turtle excluder devices in trawl nets, the olive ridley turtle will continue to experience dramatic population declines.
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