How Sea Turtles Find Their Way
The air was warm as the skies grew dark over Diego Garcia. As the nearly full moon reached its highest point, a green sea turtle scuttled her way onto the sand. The ocean giant was more than a meter wide and nearly as long from nose to tail. Her carapace, mottled with splotches of green and black, was slick with salt water.
Turtles glide through the sea with a certain reptilian elegance, but on land their awkward, plodding movements evoke a wind-up toy in need of a few more cranks. After shuffling a suitable distance from the waterline, the turtle began to excavate a shallow hole, using her arms and legs like spades to fling pebbles and sand through the air. Nearly exhausted, she finally began to relax as she released dozens of ping-pong-ball-sized eggs into the ground.
It was likely the first time in years she’d set flipper on dry land. Other than the moments after they hatch and crawl into the surf, sea turtles spend their entire lives in the ocean. Only when females return to lay eggs on the same beaches where they hatched do they leave the water—just briefly, for a few hours, before slipping back into the sea. They may lay several clutches of eggs during the mating season before setting off for their foraging territories. There they stay for several years, regaining energy by feasting on seagrass, before returning to their natal beach, mating just offshore, and beginning the cycle anew.
Turtles are born with a set of instructions that, at least most of the time, safely delivers them into the open ocean.
Having carried out the full extent of her duties as a mother, this turtle had completed a ritual that’s played out countless times on Diego Garcia, a footprint-shaped atoll in the Indian Ocean’s Chagos Archipelago. Green sea turtles have used the atoll as an incubator for hundreds or thousands
