Rock Louse (Ligia pallasii)
Rock Louse (photo credit: Biodiversity of the Central Coast)
Other Names: Sea slater, Northern sea roach
Description: The rock louse is a small flat isopod about 35mm in length and 11mm wide. Like other isopods, their body is segmented, they have two antenna, and a tail. They are often a mottled dark brown or gray and camouflage with the rocks that they live on.
Habitat: Rock louse can be found as far North as the Aleutian Island of Alaska and as far South as Santa Cruz California. They prefer to find shelter on rocks in the high intertidal zone. At Haystack Rock, the best place to look for rock louse is in rock crevices.
Diet: Scavenging for decaying plant and animal matter, rock louse help keep the high intertidal zone clean.
Tide Pool Tidbits:
Rock louse are a member of the “ancestral” or short tailed group of isopods.
In Oregon, rock louse are often found on rocky cliffs in estuaries.
Rock louse are some times harvested by recreational fisherman and used as bait.
References: Walla Walla University, Oregon Institute of Marine Biology