Freshwater Shrimp - Gammarus pulex

Alt Name
River Shrimp

A greyish or brownish freshwater crustaceangrowing to 21 mm but usually much less . Not a true shrimp, but sometimes referred to as the Freshwater Shrimp or River Shrimp.

Photo ID?

Freshwater. They prefer flowing water but have also been found in ponds.

When to see it

All year round.

Life History

The life cycle of Gammarus pulex is complex. Males grab and hold females before deciding which one is likely to produce lots of eggs. Then the male carries his chosen female for several weeks until she sheds her skin and the male can mate with her. He then lets her go and she carries the developing young in a brooding pouch. After about a month, the young shrimps swim out of the brood pouch, and a few months later they can breed themselves. As females can produce up to 50 young each month, the population soon grows.

UK Status

Fairly frequent and widespread in Britain.

VC55 Status

Status in Leicestershire and Rutland not known.

Leicestershire & Rutland Map

UK Map