Great pond snail
Lymnaea stagnalis
The shell of a great pond snail can grow up to 60mm high.

Physical description
The colour of their shells varies from yellow-brown to dark brown or grey and has a pointed spire. Their skin is dark brown or grey.

Distribution
Great pond snails are widespread in Britain and Europe. Also found in Asia, north Africa and North America.

Habitat
Great pond snails are found in slow-moving or stagnant water, more frequent in hard water. Will tolerate slightly brackish water.

Diet
They feed on algae and rotting organic matter.

Behaviour
This snail deliberately ingests grains of sand which stay in its gizzard and help it break down tougher plant material that it would otherwise be unable to digest.
They can be seen floating upside-down on the surface taking in air. They can also absorb oxygen from the water through their skin. By employing these strategies the great pond snail can stay underwater for several months.
During winter these snails burrow into the soft mud and hibernate. They withdraw into their shells and secrete a thick seal over the mouth of the shell called an epiphragm. This helps to protect them from the cold until spring when they emerge again.

Reproduction
The eggs are laid in jelly-like capsules on aquatic plants.

Conservation status
They are not listed as endangered on the IUCN Red List.
