Rock lice

Distribution in scandinavian waters

Maximum length: 3 cm.
Appearance: Rock lice have a distinctly segmented back. The antennae are long, while the extremeties of which are highly jointed. The last pair of legs on the hind, point backwards, are branched and nearly of the same length. Rock lice are the largest of the related specie. They are mainly dark brown to black in colour, but can change colour like many other crustaceans.
Depth: From the water-line and about 10 m up on land where the sea spray reaches.
Environment: Lives on cliffs and rocky beaches. Occasionally venturing into the water.
Misc: Rock lice are rather timid. Most individuals are out rumaging at night. They disappear very quickly into crevices or the water when attempts are made to catch them.
    Mainly fall prey to shore crabs and birds. Feed mostly on seaweed.
    They can be as old as 3 years, and it is at this age they mate. The young do not live as larvae in the sea, but leave their mother fully developed.
Classification: Rock lice are isopods, which are crustaceans under the arthropods.
    There are many different specie of louse that live in the sea, but rock lice are the closest relatives to the land-living woodlice.

Rock lice    Other names

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Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson