Third Grade
Worksheets
Crustaceans
Have you ever played with a roly-poly bug? Roly-polys are a kind of crustacean (crust -a- shun). Other kinds of crustaceans are crabs, barnacles, shrimp, lobsters, and crayfish (some people call them "crawdads"). Crustaceans are food for many kinds of animals, including people.
Most crustaceans live in the oceans. Some live in streams, ponds, and lakes. A few even live on land. Most crustaceans usually get their air from gills, just like fish do. Crustaceans don't have lungs. Some take in oxygen through their body covering. That's how roly-polys breathe. That's why they are found in damp places. They must keep their bodies moist to breathe.
A crustacean has a skeleton on the outside of its body. This is called an exoskeleton. It is a hard shell that protects the soft body inside. Crustaceans don't have bones inside their bodies like people do. They do not have a backbone. Animals without a backbone are called invertebrates.
