Common shrimp  (Crangon crangon)

Common and widespread (2).

The common shrimp, also known as the brown shrimp, is cryptically coloured (3); it is brown and covered with tiny flecks (2). Although most specimens tend to measure between 30 and 50 mm in length, some may grow to 90 mm. The carapace extends between the eyes into a short spine, and the flexible abdomen terminates in a tail fan (known as a 'telson') (2). The word 'shrimp' is Middle English; it may derive from the German word 'schrimpen', which means 'to shrink up', and is applied to small, weak things (4).

Very common in European waters, and found around the coasts of Britain (2).

This species occurs from the middle shore down to submerged depths of around 150m; it also extends into estuaries and typically buries into the sand (2).

The common shrimp feeds on a range of worms, molluscs and crustaceans. The sexes are thought to be separate, and the timing of breeding varies around the country (2). After mating, the female carries the eggs for 3-4 weeks in summer and up to 10 weeks in spring (2). The larvae, known as 'zoeae' are planktonic, and persist for around 5 weeks. Maturity is attained after 1-2 years, and average life span is 3 years (2). This species is predated upon by many species of fish, including cod (Gadus morhua) and whiting (Merlangius merlangus). If attacked, shrimps try to escape by means of rapid flicks of the tail (3).

This shrimp is fished commercially in some areas, including Morecambe Bay, however it is not currently threatened, and remains a very common species (2).

No conservation action has been targeted at this common species.

• Carapace: the top shell of a turtle. In arthropods (insects, crabs etc), the fused head and thorax (the part of the body located near the head) also known as ‘cephalothorax’.
• Cryptic colouration: colouration that makes animals difficult to detect against their background. The colouration may provide camouflage against a background or break up the outline of the body. Both can occur in a single animal, and tend to reduce predation.
• Larvae: stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
• Planktonic: aquatic organisms that drift with water movements; may be either phytoplankton (plants), or zooplankton (animals).

1. National Biodiversity Network Species Dictionary http://www.nhm.ac.uk/nbn/
2. Fish, J. D. & Fish, S. (1996) A student's guide to the seashore. Second Edition. Cambridge University Press, Cambridge.
3. Arnott, S.A., Neil, D.M. and Ansell, A.D. (1999) Escape trajectories of the brown shrimp Crangon crangon, and a theoretical consideration of initial escape angles from predators. The Journal of Experimental Biology, 202: 193-209.
4. Buczacki, S. (2002) Fauna Britannica. Hamlyn, London.