Cabrillo Marine Aquarium

Cooper of the Sea

Phronima sedentaria


Fun Facts

    The eyes of this amphipod are so large that they make up nearly a quarter of the entire body.

    The name amphipoda means



  The cooper of the sea is a small, translucent deep sea hyperiid amphipod of the family Phronimidae. It resembles a shrimp with a large head and eyes, jaws and clawed arms. This type of amphipod is only seen in the ocean at great depths, usually by submarine crews, and is usually only about 1 inch long.
Named after sailors who made barrels on whaling ships, a female phronima makes a barrel for her young by eating the inside of a salp, leaving only the transparent outside tunic. When finished, this amphipod deposits her young on the inside of the barrel wall. She catches food (chaetognaths, euphausiids and cnidarians) with her legs and mouthparts and shares it with her young. Eventually the young eat the barrel and swim away to live on their own.
To learn more about the cooper of the sea and the deep sea habitat, visit the Open Ocean and Deep Sea Room at the Aquarium.