Amphipod

The Amphipods are an order of malacostracan crustaceans. They have no carapace.

Amphipoda Temporal range: Eocene to Recent
Gammarus roeseli
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Malacostraca
Superorder:	Peracarida
Order:	Amphipoda Latreille 1816
Suborders
Gammaridea Caprellidea or Corophiidea Hyperiidea Ingolfiellidea

The name amphipoda means "different-footed". Unlike isopods, where all the legs are alike, amphipods have different appendage types.

Of the 7,000 species, 5,500 are classified into one suborder, the Gammaridea. The rest are in two or three other suborders.

Amphipods range in size from 0.1 to 34 centimetres (0.04 to 13 inches) and are mostly detritivores or scavengers. They live in almost all aquatic environments; 750 species live in caves and the order also includes terrestrial animals and sandhoppers such as Talitrus saltator. The largest amphipods live on the sea floor, seven kilometres down.^[1]

Reproduction and life cycle

Mature females bear a marsupium, or brood pouch, which holds her eggs while they are fertilised,^[2] and until the young are ready to hatch.^[3] As a female ages, she produces more eggs in each brood. Mortality is around 25%–50% for the eggs.^[2] There are no larval stages; the eggs hatch directly into a juvenile form, and sexual maturity is generally reached after 6 moults.^[2]