Trunkless leeches
| Trunkless leeches | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Americobdella valdiviana , a land living leech in southern Chile |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Arhynchobdellida | ||||||||||||
| Blanchard , 1894 |
The trunkless leeches (Arhynchobdellida) are an order of the leeches (Hirudinea), which live as parasites or predators of vertebrate blood or various small animals. They include the two groups of the pharynx and jaw rule .
features
The trunk of the trunk-less flukes is divided into 33 segments and a prostomium at the front end . The segments cannot be seen from the outside due to the external curling. The front suction cup is made up of the 4 first segments and the rear suction cup is made up of the 7 last segments. The male sexual opening of the hermaphrodite animals is in the ninth and the female in the tenth segment.
The pine Egeln the foregut has usually three strong, serrated jaw, those using the skin of the host or the prey is aufgeritzt. The throat leech , on the other hand, have no jaws and suck up their prey as a whole with the help of their muscular pharynx .
The coelom of the proboscis flukes is designed as a system of narrow vessels through which the hemoglobin-containing coelom fluid, which serves as blood, flows and which thus represent a secondary blood vessel system, while the primary blood vessel system is completely reduced. The two laterally running muscular main vessels pulsate and thus have a cardiac function . The space between the vessels is criss-crossed with muscle cords and filled with connective tissue.
distribution and habitat
The trunk-less flukes are distributed as parasites or predators worldwide in inland waters or on land.
Systematics
Peter Ax names the autapomorphism of the monophyletic group Arhynchobdellida as the development of the coelom into a finely branched secondary blood vessel system, which takes over the role of the receding primary blood vessel system in its entirety. They form the sister group of the trunk leeches (Rhynchobdellida) within the Euhirudinea . The trunkless leeches include the following suborders and families :
- Hirudiniformes (formerly Gnathobdelliformes)
- Erpobdelliformes (formerly Pharyngobdelliformes)
literature
- Peter Ax: The system of Metazoa II. A textbook on phylogenetic systematics. Gustav Fischer Verlag, Stuttgart / Jena 1999. pp. 65–73, chapter Hirudinea .
- Elizabeth Borda, Alejandro Oceguera-Figueroa, Mark E. Siddall (2008): On the classification, evolution and biogeography of terrestrial haemadipsoid leeches (Hirudinida: Arhynchobdellida: Hirudiniformes). Molecular Phylogenetics and Evolution 46 (1), pp. 142-154.
Web links
- Arhynchobdelliformes in: Lexicon of Biology , online edition.