Planorbarius corneus

Planorbarius corneus is known by a long list of taxonomic synonyms, the earliest of which was Helix cornea in 1758. This species formerly had 4 subspecies; Planorbarius corneus arabatzis, Planorbarius corneus corneus, Planorbarius corneus etruscus, and Planorbarius corneus grandis. P. arabatzis and P. grandis are now considered distinct species, while the other two are no longer valid as subspecies. ==Distribution==

Planorbarius corneus is distributed from western Europe, through central Europe and into the Caucasus, north into Siberia and south into the Middle East. Additionally, as the species is commonly sold in the aquarium trade, it may be found outside of its main range in ponds where they have been introduced. It is not as common in southwestern Europe. 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 islands, including Madeira, the Azores, the Canary Islands. In the Nordic countries, it has been recorded in Denmark, Finland, Sweden and Norway. In central Europe, it is found in Austria, Germany, the Netherlands, Luxembourg, Lichtenstein, Switzerland and the Czech Republic, and in southern Europe it has been recorded in Greece and Italy. In eastern Europe and the Caucasus, its range includes Albania, Armenia, Azerbaijan, Bosnia and Herzegovina, Bulgaria, Croatia, Estonia, Hungary, Latvia, Lithuania, North 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. ==Description==

Planorbarius corneus is the largest European species of ramshorn snail (family Planorbidae), with a shell typically measuring in diameter and in width when fully-grown. The shell is a reddish-brown or olive color, A protrusible siphon is present near the front edge of the shell, connecting to a chamber in which the lungs reside. The 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. All species within family Planorbidae have sinistral shells. File:Posthornschnecke (Planorbarius corneus) 2011-05-12.jpg | Together with a Lymnaea stagnalis snail. File:Planorbarius corneus eggs.jpg | Eggs, not more than one day old, together with several feeding adults. The clutch is 12 millimeters long. Also, a snail's mouth with its radula can be seen clearly. Planorbarius_corneus_eggs,_about_two_days_old.jpg | The same eggs, two days later. Snail fetuses are visible. Planorbarius corneus juvenile.jpg | Young specimen, about 3 millimeters long. ==Habitat, physiology, and ecology==

Planorbarius corneus may be found in freshwater ponds, rivers, and canals, where it clings to vegetation. The species seemingly prefers water which is slow moving, highly vegetated, and contains lots of dissolved minerals. this species stays close to shallow water, as the emergent plants growing there provide access to the surface for oxygen. This species seems to be a generalist in its diet; what they eat may depend on what is available and how hungry the animal is. It has been observed to eat the egg capsules of Anisus vortex, though this may have been incidental. ==Reproduction==

Like most freshwater pulmonates, Planorbarius corneus probably follows a yearly reproduction cycle. In a 1963 study in southern England, eggs were thought to hatch in May, with the reproductive period ending before June. In an experiment, this species was shown to lay pinkish egg masses on aquatic plants such as Elodea and Ceratophyllum, as well as on the glass walls of the aquarium. The egg masses were cylindrical or oval-shaped, and had average dimensions of . Each egg mass contained between 12–49 light yellow eggs, though by one account, this can reach up to 60. Eggs first began hatching within 31–65 days of being laid, though not all embryos hatched at once. An additional 9–21 days were observed for the final embryos to emerge from the egg capsules. In the experimenter's opinion, these observations are likely to be consistent between both captive and wild specimens. ==Parasites==

This species of snail functions as a host for several parasite species: • First intermediate host for Prosthogonimus ovatus • First intermediate host for Apatemon gracilis • First and as second intermediate host for Hypoderaeum conoideum • Intermediate host for Syngamus trachea • Intermediate host for Typhlocoelum sisowi == As aquarium pets ==

P. corneus are available from commercial breeders, and they are easy to keep, as they do not need a minimum aquarium size, do not need heating, and likewise, the tank usually does not need to be oxygenated – though it helps to supply the microorganisms that process snail manure and food leftovers. They are said to only feed on living plants when other food sources (like algae and plant detritus) have become rare. They need calcium-rich water, so depending on the water source, they need additional calcium from cuttlebones or ground egg shells. The snails can be fed with any fish food, and vegetables like spinach leaves, green lettuce leaves and zucchini slices. In case of leafy or vegetable food, leftovers should be quickly removed in order to keep ammonium and nitrate levels low. Depending on the locale, a water conditioner is needed to remove copper, chlorine and other harmful ions from the water. though this seems to be a rare occurrence, and may benefit from the inclusion of aquarium plants. ==References==