Notonectidae
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Notonectidae or backswimmers is a family of insects of the Hemiptera order. Back swimmers, or Greater Water Boatmen are hemipteran bugs. They are named backswimmers because they are aquatic predators that swim upside down. They are up to 15 mm in size. They are similar to corixidae, but can be separated by differences in their dorsal-ventral coloration, front legs, and behavior. Their dorsum convex is light colored without cross striations. Their front tarsi are not scoop-shaped and hind legs fringed for swimming.
In contrast to other aquatic insects that cling to submerged objects, Anisops deanei uses a unique system to stay submerged : using the extra oxygen supply from haemoglobin in their abdomen, instead of using oxygen dissolved in the water. The size of air bubble, that provides buoyancy, changes as the nitrogen dissolves into the blood and the oxygen is used in respiration. This helps them regulate the size of its air bubble and the concentration of oxygen inside it. [1]
The main genus of backswimmers is Notonecta- streamlined, deep-bodied bugs up to 16 mm long, green, brown or yellowish in colour. As the common name indicates, these aquatic insects swim on their backs, vigorously paddling with their long, hair-fringed hind legs.
Backswimmers are predators and attack prey as large as tadpoles and small fish, and can inflict a painful bite on human finger. They inhabit still freshwater, e.g. lakes, pools, marshes, and are sometimes found in garden ponds. They can fly well and so migrate easily to new habitats.
The Common Backswimmer is Notonecta glauca, widespread in the United Kingdom and Europe. Another species is N. maculata, distinguished by mottled brick-coloured forewings.
[edit] References
- Chinery, M. (1986) Collins Guide to the Insects of Britain & Western Europe. Collins. ISBN 0-00-219137-7.
- Fitter, R. & Manuel, R. (1986) Collins Field Guide to Freshwater Life. Collins. ISBN 0-00-219143-1.
- Hungerford, H. B. (1933) The genus Notonecta of the world. U. Kansas Sci. Bull. 21: 5-195.
