Bothrioplana

Species of Bothrioplana are small organisms, usually measuring 2–3 mm in length, but reaching up to 7 mm. The body is transparent, elongate, with a round posterior end and a truncate front end, and lacks eyes. 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. The posterior branches unite behind the copulatory apparatus and form a single branch.^[1]

The reproductive system has a pair of testes and a pair of ovaries, as well as a series of vitellaria (yolk-producing glands) that extend along the entire body. Many specimens have the male reproductive system highly reduced or even absent. As a result, parthenogenesis may occur.^[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.^[1] They feed on other small invertebrates, such as Daphnia.^[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.^[3]