Rhynchobdellida (from the Greek rhynchos, mouth, and bdellein, sucking),[1] the jawless leeches[citation needed] or freshwater leeches,[2] are an order of aquatic leeches.[3][4] 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.[5][6][7] They move by "inchworming"[8] and are found worldwide. The order contains 110 species, divided into 41 genera and three families.[8] Members of the order range widely in length, usually between 7 and 40 mm.[2] They are hermaphrodite.[2] The order is not monophyletic.[9]
| Jawless leeches | |
|---|---|
.jpg) | |
| Branchellion parkeri | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Annelida |
| Clade: | Pleistoannelida |
| Clade: | Sedentaria |
| Class: | Clitellata |
| Subclass: | Hirudinea |
| Infraclass: | Euhirudinea |
| Order: | Rhynchobdellida Blanchard, 1893 |
| Families | |
| |
Appearance and eating habits
Instead of jaws and teeth, Rhynchobdellidae have protrusible proboscises, which they use to penetrate the host's skin.[2][10] Mouths of Rhynchobdellidae species are small holes from which the proboscis can be protruded.[10] The proboscis then sucks out the desired bodily fluid from the host: usually blood or coelomic fluid in the case of invertebrate victims.[9]
Rhynchobdellidae are either sanguivorous or predatory.[citation needed] Sanguivorous species usually feed on a variety of other animals, using their proboscis to host's skin. They generate anticoagulants (like mosquitoes) and natural anaesthetia to help the feeding.[2] Predatory Rhynchobdellidae have digestive enzymes that help break down their prey, which usually consists of small invertebrates such as insect larvae or amphipods.[2]
Families
Glossiphoniidae (Freshwater jawless leeches)
The Glossiphoniidae, the freshwater jawless leeches,[citation needed] or leaf leeches (due to their shape)[11] are freshwater leeches, flattened, and with a poorly defined anterior sucker.[2] The family Glossiphoniidae contains one of the world's largest species of leech, the giant Amazon leech, which can grow up to 45 cm in length.[12] Many species show extended parental care, keeping eggs in nests or pouches and caring for and feeding the young.[2][13] They feed on both vertebrate and invertebrate animals.[4]
Piscicolidae (Fish leeches)
The Piscicolidae occur in both freshwater and seawater, have cylindrical bodies, and a usually well-marked, bell-shaped, anterior sucker.[2][4] They are parasites of fish.[11][4] The family was originally divided into three subfamilies based on species' pulsatile vesicles, but the subfamilies were disbanded in 2006.[4]
Ozobranchidae (Turtle leeches)
Ozobranchidae are primarily parasitic on marine turtles, and are sometimes merged with the Piscicolidae.[2][4]
See also
References
