Anthosoma crassum is a copepod crustacean that parasitises fish hosts, typically sharks.
Anthosoma belongs to the Siphonostomatoida, an order of copepods characterised by their tubular sucking mouths.
The female can be
The trunk is largely concealed, by overlapping plates ventrally, formed from 3 pairs of modified swimming legs, and by a pair of similar looking dorsal plates (called elytra) originating behind the head. This arrangement of plates is unique for female Anthosoma so this species is not easily confused with any other.
The male is up to 10mm in length, but is similar to the female in body form although lacking the dorsal elytra covering the trunk.