Freshwater Shrimps

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Scientific name:  Gammarus

Size:  Up to 11mm long

Distribution:  Found throughout the UK

Months seen:  All year round

Life Span:  Approximately 12 to 15 months

Habitat:  Slow moving streams and rivers.  Sometimes in ponds and lakes

Food:  Algae and organic detritus.  Freshwater shrimps are scavengers feeding on decaying plant and animal remains on the riverbed

Special features:  Freshwater shrimps, sometimes called 'scuds', 'river shrimps' or 'sideswimmers', are amphipods with a curved, flattened body.  The body has 13 segments and is usually greyish-green or orange-brown in colour.  They have seven pairs of legs and two pairs of antennae.

Freshwater shrimps can usually be found in large numbers in slow moving, well oxygenated water.

Freshwater Shrimps are a popular food for birds, fish and some insect larvae so they spend most of the day sheltering beneath stones and vegetation.  They move around by crawling, but they are also good swimmers.  Because of the shape of their body they tend to swim on their sides - hence their other common name of 'sideswimmers'.

In springtime, the males can be seen holding the smaller females as they move through the water.  The females carry their eggs inside their bodies in a brood pouch.  The eggs hatch in 21 days but the young remain in the pouch until the female moults.

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• News Archive - Killer Shrimps Discovered in UK
• Freshwater Wildlife Section
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