shellfish –n. an animal, such as a crab or oyster, that has a hard outer shell and that lives in the water

species –n. a group of animals or plants that are similar and can produce young animals or plants

parasite –n. an animal or plant that lives in or on another animal or plant that gets food and protection from it

digestive –adj. related to the process by which food is changed into a simpler form after it is eaten

stage –n. a particular point or period in the development of something

benefit –n. a good or helpful effect