Amphipods

Scientific classification:

Kingdom: Animalia

Phylum: Arthropoda

Subphylum: Crustacean

Class: Malacostraca

Order: Amphipoda

Species: Mutualistic

Family: glacial reliscts

Genus: phronima
Habitat: living in living on the ocean bottom in mud or sand association with jellyfish and salps.

Food source: bacteria on the surface of particles, or scavengers on dead animals or plants
Description of life cycle (egg to death): The reproductive period started in October, and hatchlings were released from November until July. Four cohorts were present in November. Some one-year-old females appeared to reproduce more than once. Ontogenetic niche segregation occurred from June to September, when juveniles were found in shallow water and adults were found in deep water where temperatures were below 10°C.
How does it move (if it moves): Amphipods move depends on the arrangement of their legs. Most walk upright using most of the thoracic legs but this is very slow. Swimming using the three pairs of pleopods is much faster. The speciality of amphipods is the tail-flip, a rapid escape response where the abdomen flicks the animal away after the uropods are dug into the ground.

Unique characteristics: long and skinny and flattened from side to side, but more accurately they are defined by the presence of three pairs of uropods (tail-limbs) and usually by having the first two pairs of legs modified to help with grasping food. There is no carapace; seven thoracic and six abdominal segments are visible. The head carries two pairs of antennae, the eyes which are not on stalks, and the mouthparts. Amphipods have seven pairs of walking legs of which the first four reach forward, and the fifth to seventh reach backwards. The abdomen is divided into two parts, three segments with brush-like limbs and three with short immobile rod-like uropods.
Role in the ecosystem: some of them live their lives attached to marine mammals. These whale-lice are ectoparasites which cling firmly to, and feed on, the skin of whales. Unlike other amphipods, whale-lice cannot swim so once the juveniles leave the brood chamber of the female they attach themselves close by. In addition, the amphipods were infested by several parasites, including larvae of Cystidicola sp., a swimbladder nematode that infects fish.