Water strider
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Water striders mating |
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| Leach , 1815 |
The water striders (Gerridae - colloquially and regionally also Schneider or Wasserschneider ) are a family within the subordination of the bedbugs (Heteroptera). They occur in Europe with 16 species, of which 10 species of the genus Gerris live in Central Europe . The species are very difficult to distinguish from one another.
features
Water striders are 10 to 20 millimeters long and are very similar to the stream walkers (Veliidae) with their physique . They have a very slim and elongated body that is completely covered with the finest short hairs that repel the water. The hairs on their tarsi enable the animals to move quickly on the water surface with the help of surface tension without sinking in. The rear pair of legs, which they use to control direction, and the middle pair of legs, which transmit the force for the movement, are very long. The front legs are short and are only used for grasping prey. Water striders have well-developed compound eyes and can see very well. The wings of the different species are differently developed. Even within the same species there are all variants from the lack of wings to stunted to well-developed fore and hind wings ( wing polymorphism ). Their degree of development, it was determined, is related to the intensity of the incident light during the development of the larvae. Only animals with fully developed wings can fly.
Occurrence
The animals mostly live in stagnant water and stay on the water surface mostly in large groups. However, some species have specialized in living on flowing water . The wingless species of the genus Halobates , which belong to the subfamily of sea sandpipers (Halobantinae), live on the coast all year round. But there are also species that live on the high seas. These have to lay their eggs on flotsam.
Way of life
Water striders live in moderately polluted water and need a water temperature of 11–15 ° C. They predatorily feed on various insects that fall on the water. Such animals, rowing for survival, irritate the sensitive vibrating sensory organs in the legs, whereby the prey can be located. The locomotion takes place with rapid, synchronous strokes of the oars of the middle pair of legs, whereby the animals can become very fast with up to 1.5 m / s . Jumps 30 to 40 centimeters high and wide can also be observed.
development
The water striders mate in spring through early summer. However, the females lay their eggs on plants near the water surface over several months. The larvae that hatch from it go through five larval stages. In Europe they hibernate as adult animals on land.
A pair of water striders cast shadows from the water surface "dented" by their feet
Twelve water striders collectively suckling a drowned bee
A sea sandpiper of the genus Halobates ( preparation in the collection)
Water striders mating
European species
- Aquarius cinereus ( Puton , 1869)
- Aquarius najas ( De Geer , 1773)
- Aquarius paludum ( Fabricius , 1794)
- Aquarius ventralis ( fever , 1860)
- Gerris argentatus Schummel , 1832
- Gerris brasili Poisson , 1941
- Gerris costae ( Herrich-Schaeffer , 1850)
- Gerris gibbifer Schummel , 1832
- Common water strider ( Gerris lacustris ) ( Linnaeus , 1758)
- Gerris maculatus Tamanini , 1946
- Gerris odontogaster ( Zetterstedt , 1828)
- Gerris sphagnetorum Gaunitz , 1947
- Gerris thoracicus Schummel , 1832
- Gerris asper ( fever , 1860)
- Gerris lateralis Schummel , 1832
- Limnoporus rufoscutellatus ( Latreille , 1807)
Non-European species (selection)
- Genus Sea Sandpiper ( Halobates )
- Species Potamobates anchicaya (from Central America ( Panama ) to South America ( Ecuador ))
Fossil evidence
Water striders have been identified in about 100 million years old Cretaceous amber from southwest France ( Département Charente-Maritime ). These are the oldest fossil representatives of this family. Other finds are known from the much younger Baltic amber and Dominican amber . The preservation of aquatic organisms in amber requires exceptional circumstances and is therefore very rare.
Individual evidence
- ↑ Gerridae. Fauna Europaea, accessed November 22, 2006 .
- ↑ books.google.de: The Cosmos Animal and Plant Guide
- ^ V. Perrichot et al .: Charentese Amber. In: Biodiversity of fossils in amber from the major world deposits. Manchester (UK) 2010, ISBN 978-09558636-4-6 ; Pp. 192-207.
- ↑ David A. Grimaldi: Amber - Window to the Past. New York 1996. ISBN 0-8109-1966-4 .
literature
- Georg Birukow: Daily and seasonal orientation rhythms in the water strider Velia currens F. (Heteroptera). Natural Sciences 44 (12), pp. 358-359 (1957), ISSN 0028-1042
