The animal has a pair of raised longitudinal middorsal ridges (colored white on its head). The ridges, separated by a darker pigmented area, continue back along the body for several times the length of the head then fade out. This individual is hard to focus on because it is crawling rapidly. Photo by Dave Cowles, July 2012
This view of the underside of the head (the worm is crawling on the water's surface film) shows the anterior but ventral mouth. Photo by Dave Cowles, July 2012