Olive ridley turtle
Distribution: They are found in the tropics of Indo-Pacific
and the East Atlantic Ocean. The olive ridley turtles are
commonly distributed along the sea coasts of India.
Habitat: They are found in the sea water.
Physical feature: The adult olive ridley turtle is olivebrown colour above and yellowish below. They have five or more costal shields and normally twenty seven marginal shields on carapace. Young have three distinct keels on carapace. The length may be up to 1 m and weight up to 150 kg.
Reproduction: The sexual maturity may attain between four and six years. They breed throughout the year, though peak periods may be observed during the month of January. They dig a nest of a half to one metre deep with their hind flippers. The total number of eggs laid by the females varies from 40 to 150. She may nest several times in one season before returning to her feeding area which is perhaps thousands of kilometers away. After 50 to 70 days of incubation, the hatchlings emerge en masse at night.
Behaviour: The olive ridley turtles are nocturnal nesters. The hatchlings locate the sea by orienting to the brighter horizon created by reflection of moon, sand dunes etc. and they then orient to wave direction, swim offshore and gradually get imprinted with the earth's magnetic field. Mortality is reported to be high in this period. It is reported that less than one in-a-thousand is believed to survive from hatchling to adulthood. Another interesting fact is that the adults migrate back to nest on their natal beaches, where they were born. Olive ridley turtles are particularly known for their mass nesting behaviour. Thousands of turtles come ashore simultaneously to nest. The Gahirmatha coast of Orissa is one of three places in the world where this phenomenon occurs (the others are in Mexico and Costa Rica). It is reported that 1,00,000 female turtles visit Gahirmatha coast area for the purpose of laying eggs. Loss of nesting habitats, incidental capture in fishing nets, lighting on the coast and non human predation are some of the reasons for reducing the turtle population.
Life span: The life span may be up to 100 years or more.