Meet the giant woodlouse (sea slater) that can only survive in the damp zone between land and sea <\/p>
I have a childhood seaside memory of my first sea slater \u2013 a monster of a thing scuttling over a crumbling sea wall. <\/strong><\/p> It resembled the woodlice found under the stones in my parents\u2019 rockery, but this one was so big I could see its twinkling compound eyes with ease. Was it a freak of nature? Gigantism in a crustacean? Nope, this animal, at up to 3cm long (without the antennae!), was a sea slater (Ligia oceanica<\/em>), the UK\u2019s largest woodlouse.\u00a0<\/p> The sea slater doesn\u2019t turn up in the average garden compost heap or under a woodland log, because it\u2019s a specialist of rocky coastal locations. Still, it is relatively widespread in the UK, living under boulders, cliffs and rip-rap (human-placed rocks that prevent erosion). If you\u2019re planning a trip to the beach, it\u2019s well worth looking out for them.<\/p> Comparisons with the woodlouse<\/a> are obvious because, in effect, that\u2019s what a sea slater is. However, the sea slater\u2019s broad body is a changeable canvas \u2013 yellow, green, brown or grey, and often speckled with a variety of black freckles \u2013 helping it to blend into the craggy surfaces it hugs. <\/p> It can actively adjust the pigments in its cuticle thanks to cells called melanophores. This colour change is mainly a response to light levels, possibly detected by its large, well-developed eyes, but it can react to humidity and temperature, too.<\/p> As a group, isopod crustaceans (which include the familiar woodlouse and Ligia<\/em>) have just left the sea, evolutionarily speaking at least, where most of their crustacean brethren evolved and can still be found.<\/p> Surprisingly, terrestrial isopods still rely on gills to breathe, which is why they are denizens of the dark and damp. A look underneath any woodlouse reveals that the last legless segments consist of a series of closely fitting, thin flaps called pleopods. The membranes of these flaps must be coated in a film of water \u2013 the definition of a gill \u2013 for oxygen to pass across from the air to the woodlouse\u2019s blood.\u00a0<\/p> The only significant difference \u2013 and the reason that sea slaters are not roaming the land \u2013 is that Ligia<\/em> have a particularly permeable skin and gills that are less adapted to land than other terrestrial isopods, meaning they are restricted to the thin, humid line betwixt land and sea. This exposed lithic zone is a tough place for any life to get a grip. Regularly misted with salt spray or, worse, total inundated by waves, there is little in the way of plant growth. There is also the constant risk of dehydration from both sun and wind.\u00a0<\/p> Due to these conditions, sea slaters are only seen during daylight hours if their hiding place has been disturbed. The best time to find them is on a dark, moonless night, although a bright torch beam will send them quickly scuttling for cover on their seven pairs of long legs. Just like their garden cousins, they are tempted out of their crevices at night by the lack of predators and higher humidity.<\/p> Sea slaters are scavengers and part of the beach clean-up crew, chewing up anything from their favourite brown seaweeds <\/a>to mosses, lichens<\/a> and even dead animal material. We have tended to ignore Ligia<\/em> in favour of its terrestrial cousins, which is a disservice, as not only is it larger and more eye-catching, but it is also, arguably, more interesting.\u00a0<\/p> Meet more strange sea creatures<\/strong><\/p> What are sea hares?<\/a><\/p>Where do sea slaters live?<\/h2>
What does a sea slater look like?<\/h2>
Why can’t sea slaters live on land?<\/h2>
What do sea slaters eat?<\/h2>