Marine Pill Bug     Gnorimosphaeroma oregonensis 



This cute little (3/8 of an inch) critter is a marine relative of the common pill bug that lives under rotting logs and other debris on the uplands.  Both belong to a group of crustaceans called Isopods, so named because all their legs have the same anatomy and function unlike other crustaceans whose legs may be modified for different activities.  The Marine Pill Bug is unique among marine isopods in its habit of curling up in a ball when frightened, just like it's upland cousin.


The head sports antennae and two black eyes.  Light colored legs peek out from under the body shell.  Gills are located under the shell as well.  The legs help in scavenging organic material detritus which it eats along with diatoms and the occasional eggs of other organisms.  Marine Pill Bugs in turn are fed upon by other isopods, crustaceans and fish.


Marine Pill Bugs occur in the intertidal and the shallow subtidal area under rocks, gravel, seaweeds as well as floats and docks.  Ranging from Alaska to central California they occur in moderate to low salinity waters where they can be quite numerous.


While they are hard to find when searching in the intertidal zone, they are readily attracted to lights dangled in the water by scientists to attract marine critters at night.