The mouth lies on the ventral side at about the middle of the body, as in most turbellarians, and has a short pharynx.

The intestine is tripartite, similarly to what occurs in triclads, having one anterior and two posterior branches.

Many specimens have the male reproductive system highly reduced or even absent.

[1] Individuals of Bothrioplana are usually found in stagnant water, including lakes, pools, wells, and temporary ponds, but may also occur among the moss growing on stones of rivers and brooks.

[2] Bothrioplana was at first classified as a genus in the order Proseriata, but molecular studies have revealed that it is actually the sister-group of Neodermata, the parasitic flatworms.