∞ generated and posted on 2016.09.03 ∞
Members of animal phylum Annelida.
These are the familiar earthworms but also include numerous marine varieties such as clam worms plus the fresh water bloodsucking worms known as leeches. These worms possess coelom-containing segments that give rise to the ring morphologies seen with earthworms.
The possession of this segmentation is considered to represent a greater level of anatomical sophistication than one sees with the segment-less flatworms and nematodes. In turn this segmentation can give rise to a greater degree of sophistication in movement. Earthworms additionally possess both a heart and blood that flows through vessels.