Worms in this family have slightly flattened, rounded heads and approximately cylindrical bodies. Apart from the genera, Callinera and Carinina, worms in this family have paired cerebral sensory organs located on either side of the constriction where the head joins the body. Some species are red or brown, often with distinctive white bands or longitudinal stripes, but others are small and so translucent that their cerebral organs can be seen through the skin.[1]