The Mussel Worm (Nereis vexillosa) is among the more familiar
polychaete ("bristle") worms along the west coast of North
America. Like other worms in the family Nereididae, it has two
palps on the prostomium ("snout") and four pairs of tenticular
cirri arising from the sides of the prostomium in front. Nereis
vexillosa is mainly gray in color, but with iridescent green,
blue, or even pink. It is found in the intertidal zone with
mussels and barnacles, as well as on pilings and under rocks and
pieces of wood in quiet bays. (Kozloff 1993; Sheldon 1999;
Carlton 2007) Johnson (1943) investigated the life history of
Nereis vexillosa and his publication should be consulted for
detailed information on the life history and development of this
species. The tiny eggs produced by Nereis vexillosa are about
0.2 mm in diameter; they are spawned in firm, irregular
gelatinoid masses, somewhat translucent, with blue-green,
greenish, or brownish tints. These colors are most noticeable in
the freshly laid eggs due to their gre