Great Pond Snail Lymnaea stagnalis
We do not only find snails on land. Many species live in water. Perhaps the best known is the Great Ramshorn. The Great Pond Snail is a very common aquatic species as well and reaching a height of 6 cm it is the biggest snail in fresh water in Britain. The shell is variable in colour: usually greyish to brownish and combinations of colours frequently exist. The colour of the body is variable as well, but usually dark grey or dark brown. Stagnicola palustris is very similar, but reaching some 3 cm only, much smaller.
The Great Pond Snail belongs to a group of aquatic snails called lung snails. They have a lung used for breathing. Under difficult circumstances the Great Pond Snail may breath through its skin though. This happens in winter when the water gets frozen over. But usually the snail comes to the surface in order to breath. It may glide over the surface of the water, but upside down of course, which is a rather weird sight. It feeds on rotting plant material, algae and debris, but it eats small insectlarvae and small snails as well.
Each Great Pond Snail is both male and female and is so at the same time. So after mating both animals will lay eggs. The eggs are encapsulated in gel and laid as one big mass containing up to 120 eggs. The mass is deposited on the underside of a leaf, close to the surface of the water. Many of the hatchlings are eaten by other snails or fish.
The Great Pond Snail has conquered most of the world and is a common species in Europe, Asia, North America and even New Zealand. In Britain a very common species indeed. People often keep this species in fish tanks, where they will reduce the number of algae. Never put a wild animal in your tank though, for it may carry an unwanted desease, killing your fish or other animals living in your tank. You can buy this animal in pet shops, which gives you healthy animals.