The rock pool shrimp (Palaemon elegans) is very common in our rockpools and is often confused with other shrimp species like the common prawn (P. serratus). P. elegans has a transparent body with dark brown stripes along its carapace and six abdominal segments with yellow and blue banded legs. They can be differentiated from other shrimp species by their rostrum (a long appendage that looks like the shrimp’s nose and has several serrations). P. elegans has a much straighter rostrum than P. serratus with 8-9 serrations, 2-3 are behind their eyes. These shrimp can get to 63mm in length but are usually found much smaller than that; around 30mm.
Kingdom: Animalia (Animals)
Phylum: Arthropoda (Invertebrates that have exoskeletons, segmented bodies and paired jointed appendages)
Subphylum: Crustacea (Crustaceans)
Class: Malacostraca (Segmented crustaceans that have 20 segments that are split between a head, thorax and abdomen)
Order: Decapoda (“ten-footed” crustaceans)
Family: Palaemonidae (A family of shrimp)
Genus: Palaemon (Caridean shrimp or true shrimp)
Species: P. elegans
The rock pool shrimp is a euryhaline species, meaning it can survive in a variety of salinities. They are found on rocky shores all of the UK with lots of algae and can live in varying tide pool depths. You can normally find them hiding underneath big rocks for shelter so make sure to look under them, replacing the rock where you found it after looking. Their distribution is spread from Norway, to the Baltic Sea, Mediterranean, Black Sea and the Azores. The shrimp was naturally introduced into the Baltic Sea through range expansion but their establishment has been so successful that it has started to outcompete other species like Palaemon adspersus.
P. elegans are omnivorous meaning they feed on both plant matter and on other invertebrates. They commonly feed on detritus and macroalgae, which is why they prefer habitats that are vegetated.