Emergence of Olive Ridley Turtle

The Olive Ridley (Lepidochelys olivacea) sea turtle, named for the olive tone of its carapace. It travels in the open ocean waters of tropical Pacific, Atlantic and Indian Oceans. Olive Ridleys are more abundant seaturtles, but are still on the endangered species list because only a few nesting sites remain worldwide where they can congregate for the Arribada.

Much has yet to be discovered about sea turtles, because most of a sea turtle’s life is spent submerged at sea, studying sea turtles in the wild is challenging. During nesting season, when females come ashore, we can get a rare glimpse of these animals.

Olive Ridley turtles reach sexual maturity when they are 10 --15 years of age. When it is time to mate, male and female turtles will congregate offshore of the beach where they were hatched. When a female is ready to lay her eggs, she will crawl ashore. A mother turtle is choosy about the location of her nest. She will carefully select a location above the high tide line. If she is not satisfied with the quality of the beach or if noises, strange objects or bright lights frighten her, she will return to the sea. This is called a “false crawl.”

Once comfortable with the spot for her nest, the mother turtle uses her flippers to dig a body pit in the sand. With her body in position, she cups her rear flipper and uses them to scoop out an egg cavity in which to deposit her eggs. The eggs, which resemble rubbery ping-pong balls, are laid at a rate of two to three at a time. Females will lay anywhere from 80-120 eggs per nest, depending on their species.

A great deal of care is put into camouflaging the nest once the eggs are laid. The mother will pack sand over the egg cavity and will then use her front flippers to disguise the body pit. She throws sand in all directions, making the nest virtually impossible to recognize. When the mother turtle is content that the nest is concealed, she will head back to sea. She will repeat this procedure three to five times in a single nesting season, but will, in most cases, not return to nest again for two to three years.

The eggs will incubate within the nest for approximately 60 days. The average temperature of the nest during the course of incubation will determine whether or not the young hatchlings will be male or female. Females result from warmer temperatures; males develop when temperatures are cooler. Many factors such as the quality of the sand, weather and beach development can influence the incubation temperature of the eggs.

Emergence/ Boil

When the hatchlings have fully developed, they will hatch and crawl their way up and out of the nest en masse. This event is called a “boil,” as it resembles a pot boiling over with sea turtles. Emerging hatchlings obtain bearings to the ocean by locating the horizon over the water, which is brighter than the landward horizon, and they scurry in that direction to their new home. Once these hatchlings reach the sea, their activities are a mystery to scientists. It is believed that they find floating masses predators. Before the hatchlings leave the beach, they imprint the location so they can return again as adults.

The first hatchlings of the season emerge from nests approximately eight weeks after the first nesting of the season, and this activity continues for up to eight weeks after the final nesting of the season. In Chennai, hatchlings generally emerge throughout the spring and early winter. It is a myth that hatchlings emerge only around the time of the full moon. Hatchlings ready to emerge wait just beneath the sand surface until conditions become cool. This temperature cue prompts them to emerge primarily at night, although some late-afternoon and early-morning emergences have been recorded.

The apparent brightness and glare of artificial lighting often leads hatchlings astray. To a hatchling on a beach, an artificial light source appears bright because it is relatively close by, yet it is not intense enough to brighten the sky and landscape. The resulting glare makes the direction of the artificial source appear overwhelmingly bright—so much brighter than the other directions that hatchlings will ignore other visual cues and move toward the artificial light no matter where it is relative to the sea.

Sea turtle hatchlings have an innate tendency to move in the brightest direction. Under natural circumstances, the brightest direction is most often the open view of the night sky over, and reflected by, the ocean. This sea-finding behaviour can take place during any phase and position of the moon, which indicates that hatchlings do not depend on lunar light to lead them seaward. Hatchlings also tend to move away from darkly silhouetted objects associated with the dune profile and vegetation.

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