Spooky Skeletons

Animals with skeletons inside of their bodies have endoskeletons. Organisms like amphibians, birds, mammals, reptiles, and most fish have endoskeletons. You fall into this category too! Without the support of your endoskeleton, your body would collapse into a blob, explains Steve Huskey. He’s a biologist at Western Kentucky University who studies skeletons.

An endoskeleton helps you in several ways. Some of the hard bones provide protection for vital organs. Others, like those in the legs and arms, are involved in movement. As muscles flex, they pull bones into different positions. This allows animals to move limbs and other body parts. Bones connect at joints. These structures allow you to be flexible so you can do a silly—or spooky—dance!

Animals like sharks and rays belong to a group of fish with endoskeletons. But their internal skeletons aren’t made of hard bones. Their skeletons are made of cartilage. It’s the same tough but flexible tissue that makes up the tip of your nose and ears.

A skeleton made of cartilage allows an animal’s body to bend easily. That makes it perfect for creatures that live in the water. For example, rays glide through the ocean by waving their fins up and down, like wings.

Cartilage also weighs less than bone. “When you pick up a stingray’s skeleton, you barely even know you’re holding it,” says Huskey. The lightweight skeleton lets these animals swim fast.