Turtles are one the oldest and most primitive groups of reptiles and have outlived many other species. One can only wonder if their unique shell is responsible for their longevity, did you know that their shell is made up of 60 different bones all connected together and developed from their ribs?!! Today I wanted to share a few other facts of a very interesting species, the Olive Ridley sea turtle (Lepidochelys olivacea), which nests in the
Olive ridley turtles, a medium-sized species of sea turtles found in warm, tropical waters, are known for their synchronized nesting in mass numbers, called arribadas. Females ready to nest may appear in large groups that can be made up of thousands of turtles. These large gatherings are called arribadas, a Spanish word for "arrival". Where and when arribadas will occur is unpredictable at all sites. Though this happens all over the world, in Costa Rica, this occurs on two main beaches, the Nancite and Ostional. The largest arribada recorded in history so far was in Ostional, Costa Rica and it took place in November 1995 when an estimated 500,000 females came ashore. What a stunning sight that must have been! They appear to be precipitated in part by climatic events, such as a strong offshore wind, or by certain phases of the moon and tide. Arribadas are believed to be a 'safety in numbers' natural technique to conserve the loss of newly hatched young. So many hatchlings appear in such a short period of time as a result of the great number of eggs laid, a number of hatchings can escape the predators searching for food.
Male sea turtle embryos can't stand the heat. The temperature of the sand in which the eggs are incubated determines the sex differentiation of hatchlings. Warmer temperatures yield more female offspring; cooler temperatures yield more males.
The hatchlings use an egg tooth to open the egg shell. Once out they dig their way out of the nest. Guided by the moon light, they quickly make their way to the water. Predation is heavy as they crawl to the water and swim into the shallows but they need to crawl to help their muscles prepare for swimming.
You might picture a turtle munching on lettuce or eating algea but these turtles are equipped with powerful jaws, and are actually omnivores, feeding mostly on a wide variety of invertebrates such as shrimp, sea jellies, lobsters, and crabs. They will also prey on fish. Algae is a source of food if their usual preferred diet items are in short supply. They use multiple feeding grounds, typically foraging offshore to depths of 500 ft on bottom dwelling crustaceans.
The lifespan of the olive ridley is believed to be 50 to 60 years. While it's life can be very long it is still fraught with many dangers. The mortality rate in newly hatched and juveniles is extremely high. It is estimated that only one of a thousand hatchlings reaches maturity. Predators such as small, carnivorous land animals, birds, and sharks and other fishes, prey on the baby turtles.
While they have many predators, the worst is by far humans. The biggest threats include encroachment on nesting areas by commercial and residential development, placement of lights that confuse hatchlings trying to find the water, interference to nesting sites and egg-laying females, ghost nets and other dangerous debris, and boat-turtle collisions. In areas where the turtles have been plentiful, residents have traditionally harvested adults for meat and emptied the nests of eggs for subsistence and for sale. Thousands of turtles are killed yearly by commercial fishing boats such as fish and shrimp trawlers.
Olive Ridley turtles are migratory, sometimes traveling several thousand miles between feeding grounds and nesting sites. Most commonly a female will nest on the same beach where she was hatched (nest site fidelity).
Olive Ridley turtles are named for its green/gray carapace. When viewed from above, the hard, relatively thin carapace of the olive ridley sea turtle appears broadly oval and without ridges. It is composed of a series of five to nine transverse bony plates called scutes. The number of scutes may vary relative to the geographical location of the turtle.
Olive Ridley turtles are found all over the world but the three biggest populations are found in the Indian Ocean, the eastern Pacific Ocean, and the western Atlantic Ocean. They prefer tropical and subtropical waters, but they can also be seen in colder waters as well.
Olive Ridley turtles are the most abundant sea turtle yet they are still endangered. The overall population has been reduced drastically in the last 60 years. Although the Olive Ridley turtle is legally protected in most areas where it appears, frequently little or no enforcement of laws and regulations takes place.
If you feel like observing the amazing natural phenomenon of the arribada in a responsible way please contact me and I'll be happy to help you plan your next dream adventure in Costa Rica or Nicaragua.
I'm based in Costa Rica and I love to see the turtles at least once a year. It's time to "stick our necks out" and see these amazing creatures in their natural habitat. Here is some information on from previous blogs on places and times to see this and other turtle species in Costa Rica. Hasta pronto!!
Your friendly tica,