Any of various predominantly aquatic arthropods of the class Crustacea,including lobsters,crabs,shrimps,and barnacles,characteristically having a segmented body,a chitinous exoskeleton,and paired,jointed limbs.

• 甲壳纲动物，任一种甲壳纲的数量占优的水生节肢动物，包括有螯虾、蟹、虾和藤壶等，其特征是具有节状身体、几丁质的外骨骼以及成对的、有关节的脚。