is a common reddish-grey, shallow water shrimp can reach a length of 7.5 cm. The carapace has a short rostrum and is smooth except for a mid-dorsal spine and a pair of hepatic spines. The final segment of the abdomen has a deep dorsal groove flanked by two ridges.The closely related species Crangon crangon
, is found from the intertidal to 50 m and can be found co-occuring with Crangon allmanni
. Crangon crangon
is commercially harvested in northern Europe and can be distinguished from Crangon allmanni
by its brown-grey colouration and the lack of a dorsal groove of the sixth abdominal segment.