Some pond snails have gills to breathe in water. Those with gills will live at the bottom of the pond. Those that do not have gills, will come up to the surface to breathe. These snails will live on the surface so that they can come up to breathe easily.
You can buy pond snails from a fish shop. The flesh of the snail is very delicious. The French people especially, love to eat snails. They are called escargot.
The pond snail feeds mainly on plants like algae and microscopic creatures that are found on the surface of water weeds. They eat by scraping bits off with their rough tongue just like the garden snails.