Olive Ridley Reproduction and Development

Social Structure

Olive Ridleys are solitary other than when they come together in massive groups during nesting. They rarely interact with one another outside of courtship and mating. Even when large numbers of turtles gather, there is little behavioral exchange. 

Reproduction

Mating and nesting season is from June to December. 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. Females nest on the beach where they were born. While some 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. This is called an arribada and is a unique nesting phenomenon common to both the olive ridley and kemp's sea turtle. Arribadas occur on a lunar cycle of approximately 28 days. The majority occur around the start of the last quarter moon and during the darkest nights just before the new moon. The turtles begin congregating offshore several days or weeks before they come ashore to lay their eggs on the beach. Females lay 50 to 200 eggs in each nest and return to the ocean shortly after. 

Development

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. Hatchlings use a temporary tooth-like outgrowth called caruncle, which is specially adapted to break the egg shell and falls off soon after hatching. Climbing up the nest chamber takes huge collaborative effort, with hatchlings situated at the top of the nest being pushed out by the ones beneath them. This process can take between 3-5 days. 

Hatchlings usually emerge at nightfall in order to avoid both daytime predators and heat exhaustion. As the olive ridley hatchlings make their way to the ocean guided by the moonlight reflecting on the horizon, they have a low chance of survival, facing threats from predators such as seabirds, crabs and fish. After reaching the water, hatchlings enter into a multi-day “swimming frenzy” during which they swim almost continuously, fueled only by leftover egg yolk, to reach deeper water away from shore. 

After this, little is known about the life cycle of turtles. Scientists are still unsure exactly where turtle hatchlings spend the first few months or years of their life. They probably find shelter in mats of algae, floating passively in major current systems, and feed on the surface on pelagic vegetation and animals. After one to ten years, the turtles will retreat to coastal areas where they forage and grow until maturity. Not much is known about the diet of juvenile olive ridley turtles. Because they live long, olive ridley sea turtles do not reach sexual maturity until 13 years old, making this species vulnerable to natural population declines. Once sexual maturity is reached the turtles will mate and females will travel back to the beach where they were born to lay eggs.