The olive ridley turtle (Lepidochelys olivacea) is the smallest and most abundant of all sea turtles, growing up to 70 cm and weighing 45 kg, on average. The olive ridley gets its name from its olive green coloured carapace, which is heart-shaped. Males and females grow to the same size; however, females have a slightly more rounded carapace. The turtle has 5 to 9 pairs of costal scutes and either one or two claws on each flipper. Indian Ocean olive ridley turtles are, on average, smaller than individuals found in the Pacific and the Atlantic.
Biology and Behaviour
Olive ridley turtles reach sexual maturity at approximately 15 years of age, an early age compared to other sea turtles. Many females nest every year, some twice a season, laying clutches of approximately 100-110 eggs, which take from 45 to 65 days to hatch. The nesting female leaves track marks that are 70-80 cm wide and have asymmetrical forelimb marks. Tail drag marks are absent. Olive ridley turtles use three different strategies to nest: arribadas, solitary nests and mixed strategy.
An arribada is a mass-nesting event when thousands of turtles come ashore at the same time to lay eggs on the same beach. More commonly, olive ridley turtles nest in a dispersed way (individual nesters are not synchronous). In certain places, some females can use both strategies. The time period between nesting events for solitary nesters is approximately 14 days; for arribada for arribada nesters, it is 28 days.
Olive ridley hatchlings are charcoal grey with a greenish hue along their sides. They measure around 38 mm long and weigh 17g at birth.
Olive Ridley Diet
Olive ridley turtles have a varied diet, eating algae, lobsters, crabs, tunicates, jellyfish, shrimp, fish, and fish eggs. They can dive to depths of over 150 metres to find food. In the open ocean, they eat just about anything they can find.
Habitat and Distribution
The olive ridley turtles are globally distributed in the tropical regions of the South Atlantic, Pacific, and Indian Oceans. Though mainly pelagic, yet they have been found to inhabit coastal areas, including bays and estuaries. Olive ridleys often migrate thousands of kilometres between pelagic feeding and coastal breeding grounds. Fishermen have spotted adult olive ridleys over 4,000 km from land in the Pacific.
Little is known about the juvenile stage of this turtle but it is thought to spend its first few years floating in oceanic currents and foraging for planktonic plants and animals. Satellite tracking studies of female olive ridleys nesting in Bangladesh show that they travel widely in the Bay of Bengal, coming very close to the coasts of India and Sri Lanka. The tracking of rehabilitated turtles released from the Maldives shows that they travel with the predominating currents either east towards Sri Lanka and India or north through the Lakshadweep Islands and into the Arabian Sea. Despite the enormous number of olive ridleys that nest in
Orissa, India, this species is not commonly seen throughout much of the Indian Ocean.
Olive Ridley Turtles in Maldives
There are very few documented records of olive ridley turtles nesting in the Maldives. They appear to be most common offshore and most of the recorded turtles were either sub-adults or adult females. Though previous studies report no particular season for encountering olive ridley turtles in the Maldives, more recent data suggest that this species is most often seen entangled in ghost nets between January and April. The turtles are likely on their way to or from their nesting beaches in India and Sri Lanka and encounter marine debris along the way.
Olive Ridley Turtle Conservation Status
IUCN Red List Status: Vulnerable (2008)
Sources: Hudgins, Ali, and Mancini (2017) “Marine Turtles of the Maldives: A field identification and conduct guide”. An IUCN Publication funded by USAID.