Polyclad Flatworm    Notoplana  (sp?)



You have to look closely at the photograph to find this small inhabitant of the intertidal and shallow subtidal zone.  Look below the pink thumb on the upper edge of the picture and find a tan, elongated fleshy animal stretched between the single barnacle on the left and the multiple barnacles on the right.  This is a polyclad flatworm about one inch long with it's small eyes and front end under the barnacles on the right.  It lives under rocks and oyster shells or in tidepools to keep moist when the tide goes out.  Several species of Polyclads occur on the Pacific coast of North America.


Flatworms are very common, small creatures with a simple body plan that avoid the light so they are seldom seen.     They have primitive eyes and some species have short tentacles. You may have encountered flatworms in a biology class where the freshwater form called a planaria is often studied.  There is a single opening on the underside through which both food comes in and waste goes out.  They move using cilia and muscle action over a layer of mucus much like the behavior of a common garden slug.   The larger marine flatworms have branched stomachs from which comes the name polyclad.   


All polyclads eat a variety of animals up to half their size such as limpets, barnacles and worms.  They extrude a part of the mouth called a pharynx over prey to capture and begin digestion.  Like other flatworms, polyclads are hermaphrodites with eggs and sperm present year round.  Eggs are laid from late spring to early fall.