Upon hatching from their eggs on the beach, sea turtles scramble into the sea and begin a frenzied 24-hour paddle to the deep ocean. The reason for the dash is simple and cruel: Unless baby sea turtles make it to the open ocean, they have little chance of surviving the tremendous predation that occurs on the beach and along inshore waters.
Scientists, however, have long wondered how the baby sea turtles know which way to aim. They believe the hatchlings initially orient themselves to the brighter horizon over the ocean. But once in the water, how do the green, leatherback and loggerhead turtles navigate toward open sea?
A team of researchers led by Michael Salmon of Florida Atlantic University in Boca Raton and supported by the National Science Foundation think they have the answer. The hatchlings appear to employ a unique guiding mechanism that Salmon calls a "surface wave compass." In other words, the turtles, or at least those born along Florida's east coast, head into the waves.
Salmon and his colleagues tested the theory by removing the hatchlings from the beach, hauling them seven miles out to sea and placing them in circular cages. The turtles always headed into the waves. To make sure the hatchlings were not also orienting toward stars or the moon, the researchers did the same experiment in a laboratory with artificially generated waves. The turtles still swam into the waves.
As for navigating throughout their long lives, the turtles seem to continue using visual clues and a still-to-be-explained internal compass.