Only two marine reptiles remain in today’s oceans: sea snakes and sea turtles. The sea turtles have been around for a while – about 150 million years – and have not changed much in their evolutionary history, closely resembling their fossil ancestors.

The leatherback turtle is one of seven species found in the world’s oceans, including the Andaman Sea, and is quite easy to distinguish, resembling as it does a small Volkswagen beetle. A nesting female may have a carapace two meters in length and weigh half a ton. It lacks the hard shell characteristic of other turtles; instead, it has smooth leathery carapace marked by seven longitudinal ridges.

While the male is never seen on land, some females use the northwestern beaches of Phuket for a nesting site from October through April. Egg-laying seasons are found to differ throughout the world, and sea currents may have some influence on this. Beaches with a deep-water approach, surf and a steep slope are preferred, since these features require the nesting turtle to crawl shorter distances.

The leatherback is normally a solitary animal. But during the nesting season, an offshore orgy takes place. Groups of 40-100 have been seen swimming together. The female may mate and nest up to nine times in one season, at intervals of 9-14 days.

The egg-laden female prefers to haul herself out to the ocean during the night at high tide. If there’s no disturbance, she crawls up to dry sand above the high water mark, selecting a nest site free from vegetation. She excavates a shollow body pit, her rear flippers scooping out a nest cavity with the accuracy of a precision instrument. (A turtle will abandon the nest and look for a new site if sand falls back into the cavity after it has been dug.) The neck of the vase-shaped nest is much narrower than the base. The flipper gently curves as it enters the cavity and withdraws the sand. This operation alternates from flipper to flipper until the cavity is about 50-60 centimeters deep. Such a deep nest both foils predators and protects the eggs from excessive heat and desiccation. by Terence Dillon Morin