Morphology

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.

Female

The female can be 

  • up to 15mm in length 
  • has a large head region covered by a dorsal shield
  • a trunk of 5 ill-defined segments behind the shield

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.

Male

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.