Palaemon - a prawn of rock pools

Prawns and shrimps can be quite confusing to tell a part. Often the larger ones are referred to as prawns, up to 5 cm in length. Prawn and shrimps have many similarities but the prawn has a rostrum which is an extension of the carapace, projecting between the eyes. Close-up of the rostrum of the prawn

They feed as scavengers on dead matter (often on what accumulates in rockpools) but will feed on plants and animal matter.

The exoskeleton is thin and so the organs can be seen inside. On the whole they have separate sexes and after mating the female carries the eggs beneath the body attached to the legs. She may carry as many as 4000 eggs for up to 4 months. The can live for up to four years, the zooae, planktonic larva settling out of the plankton in mid-summer, growing to maturity to breed early in the year.

P. serratus is stenohaline and thus is normally found in lower shore pools; Palaemonetes varians can tolerate a variety of salinties and is found in estuaries.

See shrimp (Crangon sp)