Sea slaters are a marine woodlouse species, and are the largest woodlouse species found in the UK as they grow to a maximum length of 3cm, although they are typically half this size. They are usually grey to brown in colour with a segmented body, black compound eyes and long antenna which are usually more than half of the body length. Also known as the Sea Roach, Sea Louse or Common Slater, their scientific name is Ligia oceanica.
They are extremely abundant throughout Britain, Ireland and the rest of Europe. They are also found along the eastern coast of North America, although they are not native to that continent and were introduced – possibly by being transported in the ballast water of ships – sometime over the last century. Sea slaters are found in the intertidal zone wherever there are rocky coastlines with heavy weed cover. This species is nocturnal and spend daylight hours living under rocks, emerging at night to feed. They mainly eat decomposing seaweed, but will also feed on any kind of dead animal matter they come across.
Sea slaters themselves make up prey for a wide range of species, with any fish which scavenges on the seabed, such as cod, whiting, wrasse, rockling, dab or flounder will feed on sea slaters given the opportunity. Despite many species of fish feeding on sea slaters they are not widely utilised as a sea fishing bait by anglers, possibly due to the difficulty of procuring a decent number of sea slaters of sufficient size to mount on a hook.