The digestive tract is complete, with a mouth and anus. The gut is roughly triangular in cross section. Protonephridia have associated solenocytes , that are homologous to flame cells. Locomotion and Feeding Cilia provide the basic power for a smooth, gliding locomotion. A degree of muscular flexion is also important, particularly during feeding, but also in predator avoidance and mating.
Some species move in a looping, leech-like fashion.
The animal is capable of reversing its ciliary beat in order to withdraw from an unpleasant stimulus. Micro-organisms including bacteria and invertebrates form most of the Gastrotrich diet, and they are sucked into the mouth by the powerful pumping pharynx. Reproduction and development Gastrotrichs are hermaphrodite organisms. Spermatophores are picked up from the male pore by the male copulatory organ, which transfers the sperm package to the female pore of the partner, who returns the action. Fertilisation takes place internally, and large eggs are produced.