Commensal worms

Commensalism is a relationship where one species lives on another and both species can benefit. In the case of commensal worms, the scaleworm will attack a predator trying to bite its host (in this case, the sea slug), and it will even fight off other scaleworms trying to hop onboard for a ride. In return, the scaleworm is able to forage on smaller organisms that live on the body of the same host, including potential parasites that could harm the host.

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