Trunk leeches
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| Blanchard , 1893 |
The trunk leeches (Rhynchobdellida) are an order of leeches (Hirudinea) that live as parasites or predators on fish or various other small animals.
features
The trunk leeches are characterized by a pointed trunk ( proboscis ) that can be pulled forward , with the help of which the skin of the host or the prey is penetrated and the blood or body fluids are sucked in. The inverted trunk rests in a cylindrical trunk sheath. The stomach of the proboscis is very elastic to absorb large amounts of blood and has paired bulges to store food. The trunk leeches have 1, 3 or 4 pairs of eyes at the front end. Some species can also have eyes on the rear suction cup.
The coelom of the proboscis is designed as a system of connected cavities (lacunae) between which there are muscle strands and connective tissue. In contrast to the pharynx and jaw rules, there is a fully developed primary closed blood vessel system , the vessels of which run within the Coelom lacunae. The blood is usually colorless.
The hermaphrodite animals exchange their sperm in spermatophores and attach it to the body of the sex partner so that the sperm can penetrate the skin.
Occurrence, habitat and species examples
The exclusively aquatic trunk leeches are distributed worldwide as parasites or predators, partly in seas, partly in inland waters or in brackish water. Almost all marine leeches belong to the family of fish leeches (Piscicolidae, formerly also known as Ichthyobdellidae).
The fish leeches have a cylindrical body and a clearly separated bell-shaped front suction cup, some freshwater species such as the common fish leech ( Piscicola geometra ) also serve as gills, vesicle-shaped coelom projections that protrude outwards. While most of the species in this family are sea creatures, the common fish leech lives in fresh water, where it attacks various species of fish. The Plattegel or Knorpelegel (Glossiphoniidae) are exclusively freshwater dwellers, unlike other leeches the brood operate and partly also carry their young with them. In addition to predators such as the small snail leech ( Alboglossiphonia heteroclita ), the large snail leech ( Glossiphonia complanata ) and the two-eyed flat cone ( Helobdella stagnalis ), there are also numerous ectoparasitic species, including the four-eyed flat cone ( Hemiclepsis marginata ), which suckles on fish and frogs , the turtle leech Placobdella costata and the duck leech ( Theromyzon tessulatum ). The turtle leeches of the Ozobranchidae family , including the Japanese and Chinese freshwater species Ozobranchus jantseanus , also suckle on limnic and sometimes marine turtles . The Ozobranchidae are only a few millimeters in size and are noticeable for their finger-shaped or tufted gills .
Systematics
Peter Ax names the development of the pharynx into a characteristic evertable proboscis as the autapomorphism of the monophyletic group Rhynchobdellida. They form the sister group of the trunkless flukes (Arhynchobdellida) within the Euhirudinea . The trunk leeches include the following families :
- Piscicolidae (fish leech )
- Glossiphoniidae ( flat leeches or cartilage leeches )
- Ozobranchidae (leeches sucking on turtles or crocodiles)
literature
- Julia Mason Stuart: Studies on the freshwater and terrestrial leeches of New Zealand. Journal of the Royal Society of New Zealand 4 (3), pp. 327-343.
- Peter Ax: The system of Metazoa II. A textbook on phylogenetic systematics. Gustav Fischer Verlag, Stuttgart / Jena 1999. pp. 65–73, chapter Hirudinea .
- Urania Tierreich , Volume 2. Urania-Verlag, Leipzig / Jena / Berlin 1966. P. 85, order Rhynchobdelliformes, Rüsselegel .
- C. Wesenberg-Lund, O. Storch: Biology of freshwater animals - invertebrates. Published by Julius Springer, Vienna 1939. pp. 350–352.
- Hugh F. Clifford: Aquatic Invertebrates of Alberta: An Illustrated Guide. University of Alberta Press, Edmonton (Alberta) 1991. pp. 70-85.
Web links
- Rhynchobdelliformes in: Lexicon of Biology , online edition.