Amphipoda

Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from 1 to 340 millimetres (0.039 to 13 in) and are mostly detritivores or scavengers. There are more than 9,500 amphipod species so far described. They are mostly marine animals, but are found in almost all aquatic environments. Some 1900 species live in fresh water, and the order also includes terrestrial animals and sandhoppers such as Talitrus saltator.

Etymology and names

The name Amphipoda comes, via the New Latin amphipoda, from the Greek roots ἀμφί ("different") and πούς ("foot"), in reference to two kinds of legs that amphipods possess. This contrasts with the related Isopoda, which have a single kind of thoracic leg. Particularly among anglers, amphipods are known as freshwater shrimp, scuds or sideswimmers.

Description

Anatomy

The body of an amphipod is divided into 13 segments, which can be grouped into a head, a thorax and an abdomen.