Piscicolid Leech

Branchellion torpedinis
Image by A. Bielecki.

Leeches are a class of annelids that has many members that feed exclusively on blood and are often found ectoparasitic on their hosts.

Branchellion torpedinis is a piscicolid leech that infects a wide range of elasmobranchs (sharks, rays, and skates). The frilly gills on the side help with respiration.

Unlike many leeches, which glue a handful of cocoons containing eggs to the substrate, this species is a supreme egg layer and instead casts large quantities of eggs into the water, more like a monogenean parasite.