Fish leech
| Fish leech | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Piscicolidae | ||||||||||||
| Johnston , 1865 |
The fish leeches (Piscicolidae, formerly also Ichthyobdellidae) are a family of leeches in the order of the proboscis leeches , which live mainly in seas , to a lesser extent in fresh water and parasitize on fish .
features
The fish leeches have a cylindrical body when at rest, which is usually clearly divided into a front region - the trachelosoma - and a rear region - the urosoma. The bell-shaped front suction cup is usually clearly separated from the rest of the body. The same also applies - but as with most other leeches - for the rear suction cup. The externally not recognizable segments usually consist of 4 to 14 rings per segment, the number changing with age. In addition to the up to 3 pairs of eyes on the head, most species also have primitive eyes on the top of the rear suction cup; they can also be present on the neck. Some freshwater species, such as the common fish leech ( Piscicola geometra ), have vesicular coelom projections that serve as gills on the Urosoma.
Development cycle
Like all other girdle worms, the fish leeches are hermaphrodites that mate with each other. They don't have penises; internal fertilization is achieved with the help of pseudospermatophores. The female sexual output is very small in fish leeches and usually hardly recognizable. The mating area (area copulatrix) can be larger or smaller or even completely absent. It is connected to a special transmission tissue through which the sperm penetrate from the pseudospermatophores attached to the mating field to the egg sacs with the egg cells in the body. The egg cocoons formed by the clitellum are mostly egg-shaped with a front and rear pin-shaped extension. The cocoons are always attached to a hard substrate with a basal plate. Brood care does not occur in the fish leeches; the young leeches hatching out of the cocoons are on their own.
distribution and habitat
The majority of the species in the Piscicolidae family are marine life . A smaller part of the species lives in brackish or fresh water , including the common fish leech ( Piscicola geometra ). The family is spread around the world.
nutrition
As ectoparasites, the fish leech infest a wide variety of fish species on which they live temporarily or permanently. In a few species, decapods serve as hosts.
Sample types
The common fish leech ( Piscicola geometra ), which lives in fresh water and is around 2 to 5 cm long, sucks on numerous freshwater fish such as whitefish , carp , pike and perch . The also limnic, but not so common, 3 to 4 cm long and 4 to 5 mm wide plate fish leech ( Cystobranchus respirans ) is considered a dangerous parasite on barbel , trout and grayling .
Systematics
The name of the family Piscicolidae is derived from the generic name Piscicola , which means "fish inhabitant" ( Latin piscis "fish", -cola "inhabitant"), while the name Ichthyobdellidae, which was often used in the past, is based on the no longer accepted Greek generic name Ichthyobdella "fish leech" goes back ( ancient Greek ἰχθύς ichthýs "fish", βδέλλα bdélla "leech").
The families Piscicolidae and Glossiphoniidae are sister groups and together form the order of Rüsselegel (Rhynchobdellida).
The Piscicolidae family includes about 43 genera , including:
literature
- Hasko Nesemann, Eike Neubert: Annelida, Clitellata: Branchiobdellida, Acanthobdellea, Hirudinea. Spektrum Akademischer Verlag Heidelberg / Berlin 1999. Piscicolidae, p. 75.
- Glenn L. Hoffman: Parasites of North American Freshwater Fishes. University of California Press, Berkeley 1967, p. 290.
- Urania Tierreich , Volume 2. Urania-Verlag, Leipzig / Jena / Berlin 1966. P. 87, Family Ichthyobdellidae, Fischegel . P. 88, Piscicola geometra, Common fish leech
- C. Wesenberg-Lund, O. Storch: Biology of freshwater animals - invertebrates. Published by Julius Springer, Vienna 1939. pp. 354–356.
Web links
- Piscicolidae in: Lexicon of Biology , online edition.