Great ramshorn

(Planorbarius corneus)



Planorbarius corneus, common name the great ramshorn, is a relatively large species of air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Planorbidae, the ram's horn snails, or planorbids, which all have sinistral or left-coiling shells. The shell of this species appears to be dextral in coiling, even though it is in fact sinistral or left-handed. Planorbarius corneus is distributed from western Europe, through central Europe and into the Caucasus, north into Siberia and south into the Middle East. In western Europe, it has been recorded in Belgium, France and the British Isles (including Britain, Ireland, the Isle of Man, Guernsey and Jersey). It is not found in Spain, but it has been recorded on some Spanish and Portuguese Atlantic islands, including Madeira, the Azores, the Canary Islands. In the Nordic countries, it has been recorded in Denmark, Finland, Sweden and Norway. Its range extends through central Europe (including Austria, Germany, the Netherlands, Luxembourg, Lichtenstein, Switzerland and the Czech Republic) into southern Europe (where it has been recorded in Greece and Italy) and eastern Europe and the Caucasus (including Albania, Armenia, Azerbaijan, Bosnia and Herzegovina, Bulgaria, Croatia, Estonia, Hungary, Latvia, Lithuania, Macedonia, Montenegro, Poland, Romania, Serbia, Slovakia, Slovenia and Ukraine). The species is also found in western Asia, having been recorded in Kazakhstan, Iran, western regions of Russia, Turkey, Turkmenistan and Uzbekistan. Additionally, as the species is sometimes sold in the aquarium trade, it is also found outside of its main range in small ponds where they have been released or placed. All species within family Planorbidae have sinistral shells. Planorbarius corneus is the largest European species of ramshorn snail (family Planorbidae), with a shell typically measuring 35 millimetres (1.4 in) across when fully-grown. The 10-17 by 22-40 millimetres (0.39-0.67 by 0.87-1.57 in) coiled shell has between 3 and 4.5 rounded whorls with deep sutures, the last whorl predominating. The upper side is weakly depressed and the lower side is deeply depressed (flattened on the underside but spire recessed on the upper side). There is no keel. The shell is light yellowish with a brown, reddish or greenish periostracum, radially and spirally weakly striated. The aperture is wide and almost circular. The animal is brown or reddish.

Taxonomic tree:

Kingdom: Animalia
Class: Gastropoda
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