crustacean

American  

[kruh-stey-shuhn] / krʌˈsteɪ ʃən /

noun

1. any chiefly aquatic arthropod of the class Crustacea, typically having the body covered with a hard shell or crust, including the lobsters, shrimps, crabs, barnacles, and wood lice.

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adjective

1. belonging or pertaining to the crustaceans.

crustacean British  

/ krʌˈsteɪʃən /

noun

1. any arthropod of the mainly aquatic class Crustacea, typically having a carapace hardened with lime and including the lobsters, crabs, shrimps, woodlice, barnacles, copepods, and water fleas

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adjective

1. of, relating to, or belonging to the Crustacea

crustacean Scientific  

/ krŭ-stā′shən /

1. Any of various widespread arthropods of the class Crustacea that live mostly in water and have a hard shell, a segmented body, and jointed appendages. Crustaceans include crabs, lobsters, shrimp, barnacles, and copepods.

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crustacean Cultural  

1. A class of arthropods with shells.

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Discover More

Crabs, lobsters, shrimp, and crayfish are crustaceans.

Etymology

Origin of crustacean

1825–35; < New Latin Crustace ( a ) (neuter plural) hard-shelled ones ( crust, -acea ) + -an

Explanation

A crustacean is a member of a class of arthropods that live in water. Some of your favorite seafood comes from crustaceans — crabs, lobsters, and shrimp. There are plenty of fish in the sea, and there are also plenty of crustaceans: strange-looking aquatic critters who usually have at least four pairs of limbs, plus a segmented body and a chitinous exoskeleton. If you think of a crust as being a little like a shell, that can help you remember crustaceans are essentially critters that have shells. Our word crust is from Latin crusta (shell or crust).

Example Sentences

"Since January, I've spent hours on the lobster every day," Gao told AFP, referring to OpenClaw's red crustacean mascot.

From Barron's • Mar. 13, 2026

The funkiest thing a “radioactive shrimp” would do—that is, if you put a radiation sensor over such a crustacean, says Pillai—is beep.

From Slate • Aug. 21, 2025

It turns out that, like the antennas on an insect or crustacean, a ray uses its tail to sense its environment.

From Salon • Feb. 10, 2025

At present, it is allowed to cut up a crustacean alive, unlike the mammals we eat.

From Science Daily • Nov. 26, 2024

The fiddler crab, that small and picturesque crustacean whose hordes move over mud flats or sand flats like grazing cattle, has no defense against the sprayers.

From "Silent Spring" by Rachel Carson

Related Words

• shellfish