Ligia oceanica
Ligia oceanica, the sea slater, common sea slater, or sea roach, is a littoral zone woodlouse, living on rocky seashores of the European North Sea and Atlantic coastlines, and is also commonly seen in Taiwan. "L. oceanica" is oval, twice as long as broad, and may reach up to in length, making it one of the largest oniscid isopods. Its colour may vary from grey to olive green, and it has large compound eyes and long antennae, two-thirds as long as its body. "L. oceanica" is found in temperate waters from Norway to the Mediterranean Sea, and  from Cape Cod north to Maine. It is a common species, occurring wherever the substrate of the littoral zone is rocky, and is especially common in crevices and rock pools and under stones. It is a nocturnal omnivore, eating many kinds of seaweed, diatoms, and detritus, with a particular fondness for bladder wrack ("Fucus vesiculosus"). "L. oceanica" individuals live for 2–3 years and usually breed only once. Genome. The mitochondrial genome of "L. oceanica" was sequenced in 2006. It is a circular, double-stranded DNA molecule, with a size of 15,289 base pairs. Although gene order is not conserved among  isopods, "L. oceanica" shows a similarly derived gene order to "Idotea balthica", compared to the arthropod ground pattern, but the positions of three tRNA genes differ in the two isopod species.