Hyperiid Amphipod

This little fellow is about 1/4 of an inch in size which is common for most amphipods.  Amphipods are a large group of shrimp-like crustaceans that are characterized by having legs that differ in shape and function and have a compressed body with their tails bent under it.  Think of the sand flea that you find feeding on drift seaweed at the upper tide line.

Hyperiids are a major group under the amphipod umbrella that can be separated from others amphipod groups by differences in the mouth parts and limbs.  However the most distinguishing feature is the very large eyes in some of the species.  The eyes of the animal in the photograph are the black structures in the upper left portion of the body.

They are mainly pelagic and most live in association with gelatinous organisms such as sea jellies, siphonophores and comb jellies.  They use their front legs to pierce the tissue of the host allowing them to enter and take up residence or move about on the surface either feeding on the host tissue or hitching a ride while gaining some protection.  Other hyperiid species are predators and have been found to eat copepods as well as young herring.