A shrimp (pl.: shrimp (US) or shrimps (UK)) is a common name typically used for crustaceans with an elongated body and a primarily swimming mode of locomotion – usually decapods belonging to the Caridea or Dendrobranchiata, although some crustaceans outside of this order are also referred to as "shrimp". Any small crustacean may also be referred to as "shrimp", regardless of resemblance.
More narrow definitions may be restricted to Caridea, to smaller species of either of the aforementioned groups, or only the marine species. Under a broader definition, shrimp may be synonymous with prawn, covering stalk-eyed swimming crustaceans with long, narrow muscular tails (abdomens), long whiskers (antennae), and slender, biramous legs. They swim forward by paddling the swimmerets on the underside of their abdomens, although their escape response is typically repeated flicks with the tail, driving them backwards very quickly ("lobstering"). Crabs and lobsters have strong walking legs, whereas shrimp typically have thin, fragile legs which they use primarily for perching.