Sea turtles have evolved a set of defenses against sharks, using their unusual shape, and their ability to flexibly change direction to evade these efficient predators. In this case, a tiger shark is shown attacking a sea turtle.

By turning its shell towards the shark as it strikes, the turtle prevents the predator from succeeding in biting it--sharks cannot open their mouths wide enough to bite a turtle when it is turned vertically. Another strategy turtles use when they are under attack by a shark, is to turn close around it. The shark is unable to grasp it, because it cannot turn so sharply. As long as the turtle stays behind the shark's head, it is safe!

The full episode that this clip was taken from can be watched here: http://bit.ly/WSVfoodchain1