'Amphipoda' (amphipods) is an order of animals that includes over 7000 described
species of small,
shrimp-like
crustaceans.
Most amphipods are
marine; although a small number of species are
limnic or
terrestrial. Marine amphipods may be
pelagic (living in the water column) or
benthic (living on the ocean bottom). Pelagic amphipods are eaten by
seabirds, fish, and marine mammals. Terrestrial amphipods such as
sand fleas can often be seen amongst sand and pebbles or on beaches.
Distribution and life
Many species of pelagic amphipods are
mutualistic or (usually)
parasitic, living in association with
jellyfish and
salps. ''
Phronima'' is a relatively common genus of pelagic amphipod that kills and cleans out the barrel-shaped body of a
salp to live inside and raise its young.

Amphopod anatomy
Of the relatively few species of free-living,
planktonic amphipods, the most abundant of all is ''
Themisto gaudichaudii''. Living in the
Southern Ocean, this amphipod congregates in dense swarms, where it is a voracious predator of
copepods and other small members of the
zooplankton.
After
copepods,
krill and
salps, which are mostly
herbivorous, the
carnivorous ''Themisto'' is the most abundant member of the
mesozooplankton in the
Southern Ocean.
In cold seas, benthic amphipods are enormously diverse and abundant. In the
Southern Ocean, amphipods are the most abundant benthic crustaceans. Some are grazers, many are
omnivorous, some even act as
piranha-like scavengers, quickly cleaning the carcasses of dead animals. Amphipods are one of the few animal groups frequently seen when
submarines venture to the deepest parts of the oceans. Other benthic amphipods are the primary food of
Gray Whales.
A ship hull fouling species of amphipod common to
Atlantic and estuarine waters is ''
Jassa falcata''.
External links
★
Amphipoda page at www.crustacea.net includes a list of families
★
The Amphipod Home Page
★
A database of amphipod literature