Estuarine Sand-shrimp (Gammarus duebeni)

Estuarine Sand-shrimp (Gammarus duebeni)

The adult is olive-brown with a laterally flattened body with a curved dorsal outline. It has black kidney-shaped eyes,  dorsal clusters of spines on the last 3 segments of its body, and 2 pairs of long antennae. When out of water it jerks along on its side. Length 16 to 22mm.

It feeds on dead plant and animal material, and hunts small invertebrates.

Found in brackish water and shores with freshwater run-off, estuaries, rocky shore pools, even lakes and rivers. It can tolarate low salinity. Locally common.

Photograph of Estuarine Sand-shrimp (Gammarus duebeni) taken April 2013, West Shore, Llandudno, Wales. © Pete Hillman 2013. Camera used Nikon Coolpix P500.

Common Prawn

Palaemon serratus

Common Prawn (Palaemon serratus)

The Common Prawn has large eyes and a translucent body with yellow, brown or reddish stripes. It has an elongate body with a fan-shaped telson (last segment, or appendage of the last segment of the abdomen). It has a large upturned rostrum with 6-7 dorsal teeth and 4-5 ventral teeth. The first two pairs of walking legs bear claws, and have red, blue and yellowish banding. It can move very quickly, and is a very inquisitive creature. Length up to 11cm.

It is a ominvore and it will eat virtually anything from dead animal life, to hunting other invertebrates, and to consuming plant material.

Found on the upper to lower shore, in rockpools, amongst seaweeds and under rocks and boulders. Our commonest prawn, it is widespread throughout. Prawns are a valuable food source, and are of extreme commercial interest.

Photograph of Common Prawn (Palaemon serratus), taken August 2015, in rock pool  Meadfoot Beach, Torquay, Devon. © Pete Hillman 2015. Camera used Nikon D3200, with Sigma 105mm macro lens.

Common Shore Crab

Carcinus maenas

Also called the ‘European Green Crab’, this crab is fairly variable in colour, but typically marbled dark green, brown or reddish. It has an angular-oval carapace with 5 teeth on each side and 3 rounded lobes between the eyes. Carapace width up to 10cm.

The Common Shore Crab is a scavenger of carrion and plant material, it also feeds on molluscs, other crustaceans and worms.

Found on all shore types middle to lower shore, under seaweed or rocks, and in rock pools. Common and widespread. Britain’s most commonest seashore crab.

Photographs taken April 2014, Llanduno, Wales and August 2015, Meadfoot Beach, Torquay, Devon

Idotea balthica

The males are larger than the females. The adult has a long, ovoid body with variable colouration, either yellow, brown or green, and typically with white spots or a longitudinal line down the centre of the dorsal surface. The females are often darker than the males. The telson (last segment, or appendage of the last segment of the abdomen), is broad and relatively large with three points at the tip, the centre one being the longest. It has straight sides and is dorsally keeled. Length up to 30mm.

It feeds on algae.

Found mainly sub-littoral, sometimes in rockpools and amongst drifting seaweed. Widespread and locally common.

Photographs taken August 2015, in rock pool  Meadfoot Beach, Torquay, Devon.