Shaggy Mouse Nudibranch     Aeolidia papillosa



Deriving it's common name from it's resemblance to a small, furry rodent, this little fellow is about two inches long, but has been reported to grow to just under five inches.  It has also been called the maned or shag-rug nudibranch.  It's cream colored body with brown spots is covered along the sides with brown stalks or cerata which are armed with nematocysts or stinging cells derived from it's prey. The white horns on the head house sensory organs. The white triangle in the front of the head is characteristic of this species.


Usually well camouflaged, it is fairly common around rocky areas, eelgrass beds and marina floats where it feeds on plumous anemones and several others including the aggregating anemone.  Usually attacking the anemone's body wall, it manages to avoid the stinging cells of its prey, by secreting a mucus, while consuming it's own weight in anemone tissue each day.


Like other nudibranchs, the Shaggy Mouse is a hermaphrodite having both sexes in one animal.


The Shaggy Mouse can be found from Alaska to southern California.  It also occurs on the east coast of North America and in Europe.  It has also been recorded on both the east and west coast of South America.  Because of it's size and abundance, it has been the object of a number of scientific studies.