They are grey-white or light brown in colour with seven pair of legs. They avoid light. Scuds can be seen in the water, sometimes in schools. Single scuds are too small to be observed closely as they are very active and move about with quick jerks of their jointed bodies. They move sideways instead of head first.
Scuds are basically scavengers.
They feed on many forms of small plant life, both living and dead. They can be found in open water and among masses of waterweeds or algae. The easiest way to collect scuds is to net out a mass of waterweeds or algae and put it into a pan. Then you remove the plants carefully, leaving the scuds and other animals in the pan. Scuds have been seen on snails, tadpoles and even the dead carcass of a water bird.