Ecomare

A parasite is an organism that obtains benefits from another organism in which it lives, its host. It usually injures the host in the process. It can be only a slight transition between symbiotes (for example the sea mat on hermit crabs), parasites and provokers of diseases (such as some bacteria, fungi and one-celled organisms). Multi-celled parasites, such as tapeworm, ribbon worms, Digenea, flatworms and nematods can accumulate in the final host via the food chain, after a number of intermediary hosts. Some crustaceans are also parasites, for example the gill parasites in fish. People have little chance of becoming contaminated with parasites in the North Sea.