Why fly? To avoid predators. They’re “basically marine popcorn,” says Steve Huskey, a biologist at Western Kentucky University and author of The Skeleton Revealed. "Everybody eats them.”

The key to their flight is a strong vertebral column and tail area, which anchors powerful muscles that move their tails back and forth, like propellers. Bones keep flying fish fins extended, allowing them to function like bird wings.

Flying fish are just one impressive example of a species with an endoskeleton, an internal skeleton typically made of bone and found in vertebrates, including mammals, birds, reptiles, amphibians, and fish. (See otherworldly photos of animal skeletons.)

These structures store crucial minerals, such as calcium; provide support to the body;