| Velia caprai | |
|---|---|
 | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hemiptera |
| Suborder: | Heteroptera |
| Family: | Veliidae |
| Genus: | Velia |
| Species: | V. caprai |
| Binomial name | |
| Velia caprai (Tamanini, 1947) | |
Velia caprai, known as thewater cricket, is aspecies ofaquaticbug found inEurope. It grows to a length of 8.5 mm (0.33 in) and is stouter than pond skaters of the familyGerridae. It is distasteful to predatory fish, engages inkleptoparasitism, and can travel at twice its normal speed by spitting on the water surface.
The adult insect grows to a length of 6.2–8.5 millimetres (0.24–0.33 in).[1] Members of the familyVeliidae resemble the pond skaters of the familyGerridae, but with stouter middle and hind legs, and a generally stouter appearance.[2]
Velia caprai has a chemical defence mechanism which is often able to prevent predation. It is so distasteful tobrown trout (Salmo trutta) that the fish will spit out anyVelia caprai it takes without causing them any damage.[3]
Velia caprai is subject tokleptoparasitism. In one study, whenever it took prey heavier than 7.9 grams (0.28 oz), other bugs of the same species joined it and successfully ate parts of the prey.[4]
One unusualbehaviour exhibited byVelia caprai is called "expansion skating", orEntspannungschwimmen (German for "relaxation swimming"), in which saliva is ejected from the insect's beak onto the surface of the water, lowering thesurface tension and allowing the insect to travel at up to twice its normal speed.[3]
Velia caprai aligns itself to the plane ofpolarised light, although the reasons for this behaviour are not clear.[5]
Velia caprai was first described as a separate species by Livio Tamanini in 1947, in amonographic revision of the genusVelia. Formerly,V. caprai and other species, such asV. saulii, were included inVelia currens (Fabricius, 1794).[6]
