There are many species of caprellids, and it is difficult to differentiate one from the other. They are all small marine crustaceans with a shell like crabs, and resembling tiny skeleton shrimps or even small praying mantises.
The head has 2 pairs of antennae, one of which has bristles used to push food towards the mouth.
The elongated and cylindrical body has 8 legs (4 at each end) fitted with hooks, which allow the animal to cling to the substrate.
The gills are found in the middle of the body, on the ventral part. If the belly is swollen, it is a female carrying eggs inside her.
There is sexual dimorphism in caprellids, with males being larger than females. Caprellids move like inchworms: they advance the front part of the body, then the rear part joins the front one, and so on.