Crustaceans are a type of invertebrate, meaning they don’t have an internal skeleton. They are also part of the arthropod family of animals. The term arthropod comes from the Greek word meaning “jointed feet,” and includes other similar animals such as insects and arachnids.
Even if you are not familiar with the terms crustacean or arthropod, you are probably quite familiar with some of the animals. Common crustaceans include crabs, lobsters, crayfish, shrimp, krill and barnacles. Most crustaceans live in water, although there are a few crustaceans that live on land. Crustaceans have a hard, external shell called an exoskeleton that protects their body.
Crustaceans have a head and abdomen. The head has antennae which are part of their sensory system. The abdomen includes the heart, digestive system and reproductive system. The abdomen also has appendages, such as legs, that are used for crawling and swimming. Many crustaceans also have claws that help with crawling and eating.