Science, Tech, Math › Animals & Nature What Is a Crustacean? Share Flipboard Email Print G&M Therin-Weise/Robert Harding World Imagery/Getty Images Animals & Nature Marine Life Marine Life Profiles Marine Habitat Profiles Sharks Key Terms Amphibians Birds Habitat Profiles Mammals Reptiles Wildlife Conservation Insects Forestry Dinosaurs Evolution View More By Jennifer Kennedy Marine Science Expert M.S., Resource Administration and Management, University of New Hampshire B.S., Natural Resources, Cornell University Jennifer Kennedy, M.S., is an environmental educator specializing in marine life. She serves as the executive director of the Blue Ocean Society for Marine Conservation. our editorial process Jennifer Kennedy Updated March 17, 2017 Question: What Is a Crustacean? Crustaceans are animals in the Phylum Arthropoda and Subphylum Crustacea. The word crustacean comes from the Latin word crusta, which means shell. Answer: Crustaceans are a very diverse group of invertebrate animals which includes active animals such as the crabs, lobsters, shrimp, krill, copepods, amphipods and more sessile creatures like barnacles. Characteristics of Crustaceans All crustaceans have: A hard, but flexible exoskeleton or shellTwo pairs of antennaeA pair of mandibles (which are appendages used for eating)Two pairs of maxillae on their heads (additional mouth parts located after the mandibles)Two compound eyes, often on stalksSegmented bodies with appendages on each body segmentGills Crustaceans are animals in the Phylum Arthropoda, and Subphylum Crustacea. Classes, or broad groups of crustaceans, include the Branchiopoda (branchiopods), Cephalocarida (horseshoe shrimp), Malacostraca (the class that is probably most important to humans, and includes crabs, lobsters, and shrimps), Maxillopoda (which includes copepods and barnacles), Ostracoda (seed shrimp), Remipedia (remipedes, and Pentastomida (tongue worms). Crustaceans are diverse in form and live around the world in a variety of habitats - even on land. Marine crustaceans live anywhere from shallow intertidal areas to the deep sea. Crustaceans and Humans Crustaceans are some of the most important marine life to humans - crabs, lobsters and shrimp are widely fished and consumed around the world. They may also be used in other ways - crustaceans like land hermit crabs may also be used as pets, and marine crustaceans may be used in aquariums. In addition, crustaceans are very important to other marine life, with krill, shrimp, crabs and other crustaceans serving as prey for marine animals such as whales, pinnipeds, and fish.