The term "prey" is often used when describing the feeding habits of marine life. But what does this term mean?
Prey, the Noun
As it is most commonly used in referring to marine life, prey is a noun that refers to something (usually an animal) that is eaten, or hunted and killed for food. An orca may eat salmon. Thus the prey of that orca is salmon.
Some animals have very specific prey types, such as the North Atlantic right whale, which feeds on a type of zooplankton called copepods. Other marine animals have more variety in their prey, such as sea otters, which may eat fish, bivalves, echinoderms and crustaceans.
Prey, the Verb
Prey can also be used as a verb to refer to an animal hunting or eating something, such as "the whale preyed-upon the salmon," or "orcas prey on salmon."