Hedgpeth's Sapsucker    Elysia hedgpethi


Although the name, sapsucker, may be similar to that of several bird species, this interesting creature is not a bird but a member of the sea slug group (technically known as Opisthobranch mollusks).  It differs from the more commonly seen sea slugs called Nudibranchs by having simple, rolled, anterior sensory horns.  It is a member of the Sacoglossa group which have a sack-like part of the gut that retains it's worn teeth.  In other mollusks the teeth are lost.  The teeth are part of a feeding apparatus, called a radula, that is common to mollusks and is used by most sacoglossans to feed on algae.  This species feeds on two kinds of green seaweed known as Codium and Bryopsis by piercing algal cells and sucking out the juices.


This little fellow is a little over an inch long, which is the about the maximum size for the species. The background color is tan to brown, but most individuals display a dominate green color with cream dots.  The upper part of the body consists of two flaps of tissue (parapodia) that are held erect in bright light.  However in dim light the folds are spread out creating more surface area (see small photograph).  Research has shown that the green color comes from the green algal cells ingested while feeding.  These cells are transported from the gut into the body where they continue to function for up to 10 days producing food for the animal.  So the behavior of opening the body folds in dim light appears to be a mechanism for providing the contained algal cells with more light.  Use of captured algal cells for nourishment of an animal is rare in nature.  The parapodia may also facilitate respiration.


Hedgpeth's Sapsucker ranges from southern British Columbia to the central Baja Peninsula, where it is an uncommon inhabitant of the shallow subtidal and low intertidal zone.