Once on its host Anthosoma crassum burrows into the skin until it is partially buried, with only its rear end protruding from the cavity it has excavated.
The rear end of an adult is visible embedded in the roof of the mouth, between the teeth, in this mako shark caught off St Helena (see photograph).
Shark skin is tough and the copepods often burrow into softer tissues such as the mouth, or walls of the gill chamber.
Anthosoma crassum attaches to the host by means of clawed antennae. These long antennae can be withdrawn into sheaths that extend back into the head of the parasite. When the antennae contract the parasite is brought into closer, more secure contact with the host.
Anthosoma crassum feeds on the tissues and blood of its hosts.
Anthosoma crassum uses its strongly clawed maxillipeds to pull itself into position, so the tubular mouth comes into direct contact with the skin of its host.The crustacean then rasps away at the skin using its toothed mandibles which lie within the tubular mouth.