crustacean

noun

crus·​ta·​cean ˌkrə-ˈstā-shən 

: any of a large class (Crustacea) of mostly aquatic mandibulate arthropods that have a chitinous or calcareous and chitinous exoskeleton, a pair of often much modified appendages on each segment, and two pairs of antennae and that include the lobsters, shrimp, crabs, wood lice, water fleas, and barnacles

crustacean adjective

Examples of crustacean in a Sentence

Recent Examples on the Web

After evolving in the sea about 500 million years ago, crustaceans expanded into a huge range of undersea niches. —Andrew Coletti, Popular Science, 12 Mar. 2026

The filmmaker came across the story of the dead crustaceans through her mother. —Georg Szalai, HollywoodReporter, 12 Mar. 2026

The nearby bay was full of the crustaceans, but back in 1921, nobody was eating them. —Chelsea Brasted, Southern Living, 12 Mar. 2026

Species documented in the Nankai Trough included 33 molluscs, 23 annelids, 11 arthropods, five ribbon worms, four echinoderms, three cnidarians, and one bryozoan — mollusks, worms, crustaceans, starfish relatives, and more, thriving in a place scientists barely knew anything about. —Ryan Brennan march 11, Kansas City Star, 11 Mar. 2026

Word History

First Known Use

1835, in the meaning defined above

Rhymes for crustacean

• ablation
• bination
• carnation
• cassation
• castration
• causation
• centration
• cessation
• cetacean
• chelation
• citation
• collation

Kids Definition

crustacean

noun

crus·​ta·​cean ˌkrəs-ˈtā-shən 

: any of a large class of mostly water-dwelling arthropods (as lobsters, shrimps, crabs, wood lice, water fleas, and barnacles) having an exoskeleton of chitin or chitin and a compound of calcium

crustacean adjective