This is a relatively small sea scorpion which reaches a maximum length of 17.5cm. It has a distinctive barbel at the corners of the mouth and a long spine in front of the gill cover. The lateral line is spiny but there are no spines either side of it. The colour is very variable and changes to camouflage with the surroundings. It is often red with pink mottling when living on rock covered in pink coralline algae and greenish-brown when living amongst brown seaweed. This species is sometimes confused with the bull rout (Myoxocephalus scorpius
) but can easily be distinguished by the presence of a barbel at the corners of the mouth. The Norway bullhead (Taurulus lilljeborgi
) is very similar but tends to occur in deeper water (below 20m) and is confined to the coasts of Scotland and Northern Ireland. In the Norway bullhead there is a row of spines on the skin above the lateral line.