Arenicola marina
commonly called the lug worm, Arenicola Marina, is a large marine worm that is a pholycaete. It can grow to 9 inches off the coast of Europe and 3- 12 inches off the coast of the U.S. Like most Annelids the lug worm has a segmented body, however its nervous system is unique. Like most annelids it has 2 main ventral nerve cords, and ganglia with branching off nerve cords in the segments. However the Lug worm and other pholycaetes have brains that are more advanced than other annelids and at the upper part of the head instead of the pharynx. The pholycaete's have chemo receptors , photo receptors and other sense like other annelids, however they have ciliated structures for chemosensors, and more advanced photoreceptors that can constitute a primitive eye. |