Individuals live for 3–5 years in groups of about 40 in rocky crevices at depths of up to 40 metres (130 ft). Females grow faster than males, and the population is highly seasonal, with a pronounced peak in the autumn. They are preyed upon by a variety of fish. They can be found all around the UK and are often trapped in rockpools.
P. serratus may be distinguished from other species of shrimp by the rostrum, which curves upwards, is bifurcated at the tip and has 6–7 along its upper edge, and 4–5 teeth on the lower edge. P. serratus is pinkish brown, with reddish patterns, and is typically 100 millimetres (3.9 in) long, making it the largest of the native shrimps and prawns around the British Isles. These patterns may not be seen until it is out of the water and looked at under closer inspection as it has a transparent body.