Skeletons are not just decorations for Halloween. They give our bodies structure and shape. They protect our organs. They give muscles something to grab onto so we can move around. Some skeletons do all this work hidden away beneath the skin, but other animals wear their skeletons on the outside.
Suits of Armor
A skeleton on the outside is called an (means “out”). The exoskeletons of insects, spiders, crabs, and lobsters are made of a tough, flexible material called chitin. Other animals, such as shellfish and snails, build shells out of calcium. But whatever the material, it’s hard to beat an exoskeleton for protection—the owner’s whole body is tucked safe inside. Exoskeletons also keep the animals inside from drying out.
