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Olive Ridley Sea Turtles

Olive Ridley Sea Turtles

Hilights

  • Scientific Name: Lepidochelys olivacea
  • Status in the Wild: Threatened
  • Habitat: Oceans
  • Diet: Omnivore

The Olive Ridley, also known as the Pacific Ridley, is one of only seven sea turtle species in the world. Named after H.N. Ridley, who first reported Olive Ridley sightings in Brazil, they are the smallest of all marine turtle species. They typically measure around two feet long and weigh between 70 and 100 pounds. A small head, large scutes and heart-shaped shells characterize this species, which also have clawed flippers. True to their name, adult Olive Ridleys are dark gray-green in color, though juveniles are mostly charcoal gray.

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Olive Ridleys are omnivores, feeding on crustaceans, fish, mollusks and the occasional jellyfish. When food is scarce, they also eat algae, and a 1998 study by the U.S. National Marine Fisheries Service revealed that the species might exhibit cannibalistic tendencies. Their life span is estimated between 50-60 years in the wild. While both sexes appear similar, males can be distinguished from female Olive Ridleys by their long tails, which stick out beyond their shells.

Habitat: 

Olive Ridley turtles live in the tropical and subtropical waters of the Pacific, Atlantic and Indian Oceans, ranging from Baja California south to Chile, and along the east coast of India. They nest almost exclusively in the northern Indian Ocean (on the Coromandel Coast and Sri Lanka) and in Mexico, Nicaragua, and Costa Rica. 

Costa Rica Nesting Sites:

Olive Ridleys are most common at Ostional Wildlife Refuge, which hosts tens of thousands of turtles during mass nesting periods known as arribadas between June and December, and Playa Nancite in Santa Rosa National Park, from August through November. Other nesting sites include Playa Junquillal (July-November), Ballena National Marine Park (May and September), Playa Hermosa Wildlife Refuge (June-November; peak September-November), Camaronal Wildlife Refuge (year-round), Corcovado National Park (August-October; peak in September and October), and Playa Grande (November-March).

Reproduction: 

The Olive Ridley nesting season ranges worldwide from June to December, with peak periods in September and October. Recent research in Costa Rica has shown that Olive Ridley turtles mate close to nesting grounds and in open waters – as far as 620 miles from the nearest beach. Mating occurs throughout the year, but nesting is restricted to arribadas, or certain periods when turtles arrive en masse to beaches around the world. Nesting beaches are commonly flat and free of debris, and while Olive Ridley turtles show some beach fidelity, they do not always return to their natal beach.

Females usually nest twice per season, laying clutches of more than 100 eggs each time, which incubate for 52-58 days. Interestingly, eggs that incubate at 87.8-89.6º F produce only females, while eggs that mature at 84.2-86º F result only in males. After the incubation period, hatchlings emerge and make their way to sea. 

In the wild, caimans, coatis, raccoons and coyotes pillage Olive Ridley nesting sites, devouring the eggs. Of those that survive, many hatchlings die on their journey to the beach, falling prey to vultures, crabs, iguanas and other beach wildlife. Once in the water, they are vulnerable to sharks, fish and crocodiles. Adult turtles have few natural predators. 

Status in the Wild: 

The U.S. Federal Endangered Species Act lists Olive Ridley turtles as a threatened species, although the International Union for Conservation of Nature (IUCN) and Natural Resources classifies them as critically endangered. 

Humans are considered the greatest worldwide threat to these marine turtles. Populations have declined more than 30%, and due to tourism and other factors, Olive Ridleys are faced with dwindling nesting sites. Nearly 15 years ago, Costa Rica initiated the Egg Harvest Project (EHP), a government-sponsored program that has increased the successful hatching of turtles in Ostional Wildlife Refuge by some 20% over the last decade. Continuing conservation efforts are mandatory to keep nesting beaches protected. 

Olive Ridley Sea Turtles in Pictures