Scientific name: Gammarus
Size: Up to 11mm long
Distribution: Found throughout the UK
Months seen: All year round
Life Span: Approximately 9 - 12 months
Habitat: Slow moving streams and rivers. Sometimes in ponds and lakes
Food: Algae and organic detritus
Special features: Freshwater shrimps (sometimes known as 'scuds') are amphipods with a curved, flattened body. They are greyish, green or an orange-brown colour. There have seven pairs of legs and two pairs of antennae.
Freshwater shrimps tend to prefer slow moving, well oxygenated water, where they can often be found in large numbers.
The shrimps are a popular food for birds, fish and some insect larvae so they tend to spend most of the day 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.