Water bugs
| Water bugs | ||||||||||
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Water scorpion ( Nepa cinerea ) |
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| Systematics | ||||||||||
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| Scientific name | ||||||||||
| Nepomorpha | ||||||||||
| Popov , 1968 |
Water bugs (Nepomorpha) are a group of bug species (Heteroptera) that are found worldwide and all live in fresh water . They only leave the water when they change location or go ashore to winter. They only appear on the surface of the water for a short moment when breathing. Some species are even adapted so that they can live permanently under water.
Systematics
The Nepomorpha are next to the Leptopodomorpha , Gerromorpha , Dipsocoromorpha , Pentatomomorpha , Enicocephalomorpha and Cimicomorpha a suborder of the bedbugs . They include the families of the scorpion bugs (Nepidae), the giant bugs (Belostomatidae), the row bugs (Corexidae), the swimming bugs (Naucoridae), the back swimmers (Notonectidae), the dwarf back swimmers (Pleidae), the ground bugs (Aphelocheiridae) and those not in Gelastocoridae and the Ochteridae, which are represented in Europe and are adapted to shore habitats .
features
Characteristic of these aquatic insects are, in addition to special breathing facilities and the non-wettability of the body, a streamlined body shape and mostly clearly formed swimming legs. Their antennae are greatly shortened and cannot be seen from above. In addition to very small forms such as some representatives of the row bugs (subfamily Micronectinae ), some of which measure less than 2 millimeters, there are also the world's largest types of bugs within the Nepomorpha. These especially tropical giant bugs (Belostomatidae) can reach a body length of over 10 centimeters. Another characteristic feature of water bugs are the often well-developed forewings. The wing coverts ( hemielytras ) show the structure characteristic of bed bugs and usually carry a supply of air that is necessary for breathing.
nutrition
All water bugs are predators with little specialization in certain animal foods. They grab their prey and suck it out with the help of their piercing-sucking mouthparts, the proboscis. An exception are some representatives of the row bugs (e.g. Corixa genus ), which feed on plant and animal detritus and algae . The single-limbed feet ( tarsi ) of the front legs are designed like shovels; With them, plant waste lying on the ground is fed into the mouth.
breathing
Scorpion bugs often have a body-length, rigid breathing tube on their abdomen, which they stick out of the water surface. The breathing opening is at the end of the breathing tube. The giant bugs also have such a breathing device, which can be actively stretched out or drawn in with the help of special muscles. All other water bugs do not have such a breathing tube. The body of row bugs, back swimmers, dwarf back swimmers and swimming bugs is covered by a film of air that is held on the back by the wings and on the underside by water-repellent ( hydrophobic ) hairs. Due to total reflection at the interface between air and water, the underside appears shiny silver. This air supply is used for breathing and additionally supplies oxygen according to the principle of the physical gill . Ground bugs colonize the bottom of high-current and thus oxygen-rich waters. They never come to the surface. They take in oxygen directly from the water through skin respiration .
Locomotion
Most of the species are so-called nectic animals. They move with the help of swimming legs and thus reach the surface of the water to breathe. Not all water bugs are good swimmers. The ground bugs live buried in layers of sand on the ground. Only when they suffer from a lack of oxygen do they come out of the underground, crawl to other places or even swim. Water scorpions and dwarf swimmers don't like to swim. Usually they sit on the ground and only climb to the surface of the water to breathe on aquatic plants. Swimming facilities such as webbed hair are not very common in the families mentioned. Good swimmers, on the other hand, are the swimming bugs, the giant bugs and the back swimmers with well-trained swimming legs. The last pair of legs is the actual rowing organ. The rails ( tibia ) and feet ( tarsi ) are covered with stiff bristle hair. When the legs kick back, the hair bristles spread and enlarge the rowing area. Some types of row bugs are very agile and active. Due to their low specific weight, they have a huge buoyancy. In a sense, they shoot through the distance from the bottom of the water to the surface and are even able to pierce the surface membrane and go straight into flight. The thighs ( femur ), splint and foot of the hind legs are very strongly developed, broadly flattened and provided with a thick layer of long, bristle-like swimming hairs. Many species are good fliers, such as the back swimmer, but many representatives of the water bugs are unable to fly due to their reduced wings.
Names
The group of water bugs was previously called "Hydrocorisae". The shortened antennae of the representatives of this group also led to the name “Cryptocerata”, which is no longer in use today.
Fossil evidence
The oldest fossil water bug ( Paraknightia magnifica Evans , 1953) was found in the Upper Permian, Australia. From the Malm of southern Germany, a genus that is extremely similar to its recent relatives (including Mesonepa minor Handlirsch , 1926) is known. Furthermore, finds were made in the Upper Jurassic of England and in the Eocene moler of Denmark and the Baltic amber of the same age .
swell
Individual evidence
- ^ Arno Hermann Müller: Textbook of Palaeozoology. Volume II Invertebrates, Part 3. Fischer Verlag Jena 1978.
- ^ Sven Gisle Larsson: Baltic Amber - a Palaeobiological Study. Entomonograph Volum 1, Klampenborg (DK), 1978. ISBN 8787491168 .
literature
- E. Wachmann , A. Melber & J. Deckert: Bugs. Volume 1: Dipsocoromorpha, Nepomorpha, Gerromorpha, Leptopodomorpha, Cimicomorpha (Part 1), revision of the bugs in Germany, Austria and German-speaking Switzerland, Goecke & Evers, Keltern, 2006. ISBN 3-931374-49-1
- KHC Jordan: Water bugs. The New Brehm Library, Leipzig, 1950.
Web links
- Nepomorpha. Fauna Europaea, accessed December 4, 2006 .