What is "isopoda"

Isopoda \I*sop"o*da\, n. pl. [NL. See Iso-, and -poda.] (Zo["o]l.) An order of sessile-eyed Crustacea, usually having seven pairs of legs, which are all similar in structure.

Note: The body is usually depressed, with the abdominal segments short, and often consolidated in part. The branchi[ae] are on the abdominal appendages. The group includes the terrestrial pill bugs and sow bugs, with numerous marine forms. See Arthrostrata, Gribble.

Isopoda is an order of crustaceans which includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land, and most are small greyish or whitish animals with rigid, segmented exoskeletons. They have two pairs of antennae, seven pairs of jointed limbs on the thorax, and five pairs of branching appendages on the abdomen that are used in respiration. Females brood their young in a pouch under their thorax. Isopods have various feeding methods: some eat dead or decaying plant and animal matter, others are grazers or strain food particles from the water around them, a few are predators, and some are internal or external parasites, mostly of fishes. Aquatic species mostly live on the seabed or bottom of freshwater bodies of water, but some more derived taxa can swim for a short distance. Terrestrial forms move around by crawling and tend to be found in cool, moist places. Some species are able to roll themselves into a ball to conserve moisture or as a defence mechanism.

There are over 10,000 species of isopod worldwide with around 4,500 species found in marine environments, mostly on the seabed, 500 species in fresh water and another 5,000 species on land. The order is divided into eleven suborders. The fossil record of isopods dates back to the Carboniferous period (in the Pennsylvanian epoch), at least 300 million years ago, when isopods lived in shallow seas. The name Isopoda is derived from the Greek roots (, meaning "same") and (, meaning "foot").