As they slip from Florida's beaches into the mighty North Atlantic, newly hatched loggerhead turtles certainly look helpless: Though they navigate using Earth's magnetic fields, some of the ocean currents on which they're carried move quicker than they can swim. But just a small amount of flipper flapping keeps them on course, according to a new study. Researchers let hundreds of thousands of virtual hatchlings loose in a computer-simulated ocean circulation model. Some drifted passively; others were programmed to swim for 1 to 3 hours each day in directions similar to those chosen by real-life hatchlings in a previous experiment (shown) in which they responded to magnetic fields simulating those found at various points in the North Atlantic. Even a minimal amount of swimming profoundly affected the turtles' trajectories, the researchers report online today in The Journal of Experimental Biology. Turtles that swam for just 2 hours a day were on average 106% more likely than drifters to reach the Azores, a productive foraging area. They were also more likely to stay in the warm-water currents that are favorable for survival, avoiding areas where the most predators lurk.
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