The nereis plagelica is a skinny type of ragworm. It is mostly found in a tidal habitat, under rocks by the water, in sand or in muddy substrates. It is only about 6-21cm. in length,but it can be divided into 30-100 segments. It has two distinct appendages on its head and a visible blood vessel along the back of its body. It also contains closely positioned legs that run along the sides of the body. The muscular system of this species has been studied closely, because it works faster than most annelida and has a higher metabolism.
http://www.seawater.no/fauna/annelida/pelagica.html
http://www.int-res.com/articles/meps/1/m001p249.pdf
http://www.seawater.no/fauna/annelida/pelagica.html
http://www.int-res.com/articles/meps/1/m001p249.pdf