Rock-Eating Reptile

American alligators dive down in water to catch prey like fish and turtles. Before diving, they breathe air into their lungs. Scientists at the University of Utah recently learned the reptiles have a neat trick to stay underwater longer: They swallow rocks!

The researchers timed the dives of captive alligators before and after they ate stones. The dives lasted 88 percent longer after the rocky meals. Why? The rocks add weight to the gators. That causes them to sink even when they have more air in their lungs. The extra air lets them dive for longer. Without the stones, the air would cause the alligators to float. 

Scientists suspect alligators throw up the stones later. “Much about these animals remains a mystery,” says study leader Colleen Farmer.