Bristle leeches
| Bristle leeches | ||||||||||
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| Systematics | ||||||||||
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| Scientific name | ||||||||||
| Acanthobdellida | ||||||||||
| Pit , 1851 |
The bristle leeches are an order (Acanthobdellida) and at the same time a family (Acanthobdellidae) of the leeches (Hirudinea), which live as parasites on fish . There are two known recent species that are found in cold inland waters in the northern hemisphere .
features
The bristle leeches have 29 segments. They are the only representatives of the leeches to have bristles ( Chaetae ), from the second to the sixth segment, which are used in particular for anchoring to the host or substrate. The bristle leeches have only one rear suction cup formed by four segments , with which they attach themselves to the host, while a suction cup is missing on the mouth. In the bristle leeches, the esophagus is hardly separated from the rest of the intestine, which also has no blind sacs.
The coelom of the bristle leeches has partitions between the segments, as with the few bristles and multiple bristles. There is a fully developed primary closed blood vessel system through which blood flows with hemoglobin dissolved in plasma . The nephridia do not have capsules with amebocytes.
Occurrence, habitat and species examples
The bristle leeches are common in inland waters of Scandinavia , Siberia and Alaska as parasites on freshwater fish. While Acanthobdella peledina has a distribution area from Scandinavia to Alaska, Acanthobdella livanowi occurs only on Kamchatka and the Chukchi Peninsula .
Systematics
Peter Ax names the autapomorphism of the monophyletic group Acanthobdellida as the absence of the prostomium and peristomium, the function of the Chaetae to anchor to the host and the absence of nephridial funnels. The bristle leeches form the sister group of the bristle leeches Euhirudinea within the subclass of leeches . They include the following two types :
- Acanthobdella peledina
- Acanthobdella livanowi (or Paracanthobdella livanowi )
literature
- Peter Ax : The system of Metazoa II. A textbook on phylogenetic systematics. Gustav Fischer Verlag, Stuttgart / Jena 1999. Chapter Hirudinea , pp. 65–73.
- Adolph Eduard Grube : The families of the Annelids with details of their genera and species. Verlag der Nicolaischen Buchhandlung, Berlin 1851. S. 116, XXVI. Family Acanthobdellea Pit.
- Urania Tierreich , Volume 2. Urania-Verlag, Leipzig / Jena / Berlin 1966. P. 80, order Acanthobdelliformes, Borstenegel .
- C. Wesenberg-Lund, O. Storch: Biology of freshwater animals - invertebrates. Published by Julius Springer, Vienna 1939. p. 368, order Acanthobdellae .