Two-eyed platter
| Two-eyed platter | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Helobdella stagnalis | ||||||||||||
| ( Linnaeus , 1758) |
The twin-lens reflex Plattegel ( Helobdella stagnalis ) is a species in the family of Plattegel (Glossiphoniidae) extending by sucking in particular annelids , insect larvae , flea crabs and water lice fed.
features
The light, monochrome gray-orange colored body of the two-eyed cone is about 1.2 cm long and has a small, firm, light or dark horn plate in the middle in the front quarter of the back. He has a pair of eyes. In contrast to the great snail leech , it has neither longitudinal ridges nor warts.
Occurrence
The two-eyed flat cone is common as a cosmopolitan freshwater species on all continents with the exception of Australia. Its habitat includes particularly eutrophic waters, where it can often be found under stones.
Way of life
The two-eyed flat cone feeds mainly on little bristles, especially of the Tubifex genus and insect larvae such as mosquito larvae ( Chironomus ), but also on amphipods , water lice ( Asellus aquaticus ) and various water snails . Compared to the large snail leech, the two-eyed flat cone eats more mosquito larvae and fewer snails and woodlice. The prey animals are usually sucked out completely, so that the two-eyed flat cone can be classified as a predator rather than a parasite .
Development cycle
Like all leeches, the two-eyed flat leech is a hermaphrodite . Mutual mating takes place in spring. A few days later, each of the two partners produces 3 to 5 egg cocoons that contain several yolk-rich eggs with a surrounding translucent shell. The cocoons are attached to the stomach by the mother and carried around. When the eggs come into contact with potential predators, the mother arches her body completely around the brood, creating a temporary brood cavity. After hatching, the larvae attach themselves to the mother's belly. A few days later, the now about 1 mm long young take the shape of a leech. Then the 10 to 20 young leeches can be carried around by the mother for another 3 to 4 weeks, to whose belly they attach themselves with their rear suction cup. The mother grabs prey by rolling them up in her front body, thus enabling her young to dig their proboscis into the victim and thus participate in the meal. Sometimes she also hands a captured Tubifex to her young and fills them with oxygen-rich water while they suck the victim away. The young leeches leave the mother when they have reached about a third of their body length. At first they go hunting together, later individually.
literature
- Ulrich Kutschera : Comparative brood care behavior in leeches. In: Ulrich Kutschera: Evolutionary Biology. UTB, Verlag Eugen Ulmer, Stuttgart 2008, pp. 194–196.
- Vilmut Brock, Ellen Kiel, Werner Piper: Aquatic fauna of the north German lowlands: Identification key for aquatic macroinvertebrates, with over 500 images . Blackwell Wissenschafts-Verlag, Munich 1995. pp. 43, 139
Web links
Individual evidence
- ↑ AJ Martin, RMH Seaby, JO Young (1994): Does body size difference in the leeches Glossiphonia complanata (L.) and Helobdella stagnalis (L.) contribute to co-existence ?. Hydrobiologia 273 (2), pp. 67-75.