Rhynchobdellida
Rhynchobdellida, the jawless leeches or freshwater leeches, are an order of aquatic leeches. Despite the common name "freshwater leeches", species are found in both sea and fresh water. They are defined by the presence of a protrusible proboscis instead of jaws, and having colourless blood. They move by "inchworming" and are found worldwide. The order contains 110 species, divided into 41 genera and three families. Members of the order range widely in length, usually between 7 and 40 mm. They are hermaphrodite. The order is not monophyletic.
Appearance and eating habits
Instead of jaws and teeth, Rhynchobdellidae have protrusible proboscises, which they use to penetrate the host's skin. Mouths of Rhynchobdellidae species are small holes from which the proboscis can be protruded. The proboscis then sucks out the desired bodily fluid from the host: usually blood or coelomic fluid in the case of invertebrate victims.Rhynchobdellidae are either sanguivorous or predatory. Sanguivorous species usually feed on a variety of other animals, using their proboscis to host's skin. They generate anticoagulants and natural anaesthesia to help the feeding. Predatory Rhynchobdellidae have digestive enzymes that help break down their prey, which usually consists of small invertebrates such as insect larvae or amphipods.