Consider the baby sea turtle: Just a few inches long, it emerges from its sandy nest and, using the moon as its compass, runs down the sandy beach away from its many predators and into the relative safety of the ocean surf.
The faster these little guys run, the more likely they will survive sea gulls, crabs, snakes, rats and a long list of other animals waiting to eat them. And so, these primarily aquatic animals have developed mechanisms that allow them to move at speeds of several body lengths per second on both sandy and firm terrain.
To better understand how the sea turtles' flippers work on land, researchers at Daniel Goldman's CRAB Lab (Complex Rheology and Biomechanics) at Georgia Tech studied the movements of just-hatched sea turtles on the beach of Jekyll Island, a coastal island of Georgia.
The researchers noticed that the sea turtles were able to maintain the same speed on both sandy and firmer terrain, by bending their wrists on sandy ground and keeping their wrists rigid when running on hard ground.
In order to study their movements more closely without bringing baby sea turtles into the lab, one of Goldman's students built FlipperBot, a robot model of a baby sea turtle that has the ability to bend its wooden flipper wrist or keep it rigid.
After putting FlipperBot through a number of tests, the scientists found that Mother Nature, and the baby sea turtles, have got it right. The robot was able to traverse a manufactured poppy seed terrain more quickly when it was allowed to bend its wrist. They also found that the robot, as well as the baby sea turtles, slowed down when they encountered previously disturbed poppy seeds or sand.
So, why does this matter? Well, the research can help engineers design robots that can successfully traverse many types of terrain. It might also help turtle conservationists understand what conditions can slow down baby turtles during that all-important first run, and finally, it may even help answer some evolutionary questions.
"There have been a number of organisms that have been dug up in the past year that are implicated in being some of the first organisms that climbed out of the ocean, and they have flipper-like appendages," Goldman told the Los Angeles Times. "FlipperBot can put some detail and sharpen some of the statements about how these animals would have moved on land."
And if anyone is wondering why the scientists used poppy seeds rather than sand to test the robot's movements (I was!), Goldman said it is because poppy seeds don't clog robotic gears, and it's also easy to come by and pretty cheap -- about $100 for a 100-pound bag.