Turbellaria are a group of generally small (<1 - 60cm) and free-swimming members of the flatworm phylum Platyhelminthes. Their locomotion depends on cilia. Most turbellaria are carnivorous, and actively scavenge for food. Most species are marine and freshwater dwellers, but some have evolved to dwell on humid land, as well. Classes Monogenea Trematoda Cestoda Turbellaria The flatworms (Platyhelminthes, Greek platy: flat; helminth: worm) are a phylum of relatively simple soft-bodied invertebrate animals. ... cross-section of two cilia, showing 9+2 structure A cilium (plural cilia) is a fine projection from a eukaryotic cell that constantly beats in one direction. ... Jump to: navigation, search Carnivores are animals that eat a diet consisting only of meat, whether it comes from live animals or dead (scavenging). ...

Planarian (Dugesia)

The planarian Dugesia is a common representative of Class Turbellaria. This common flatworm can be found in freshwater habitats. Their digestion tract consists of a central tubular pharynx. Each branch consists of ceca, which delivers the nutrients to the body. This worm is blind-ended, meaning there's only one way in and one way out; it consumes food where the feces exits (Gilbertson, 1999). Sideview of a planarium. ... The pharynx is the part of the digestive system of many animals immediately behind the mouth and in front of the esophagus. ... Nutrients and the body A nutrient is any element or compound necessary for or contributing to an organisms metabolism, growth, or other functioning. ...

Planarians have ocelli (eye spots) that detect the amount of light in the nearby environment, and auricles (ear-like flaps) that detect the amount of water current.

References

• Gilbertson, Lance; Zoology Lab Manuel; McGraw Hill Companies, New York; ISBN 0-07-237716-X (fourth edition, 1999)