Molluscs are invertebrates that usually have a shells, such as snails or mussels and they do an important job in your ponds ecosystem.
There are two types of pond snail; Ramshorn snail (Planorbis corners) which eats algae and rotting vegetation from the sides of the pond and the Trapdoor snail (Viviparous viviparous) which, as the name suggests, is at home on the bottom of your pond eating the same.
Swan Mussels (Anodonta cygnea) and the slightly smaller Painters mussel (Unio picture) are filter feeders. They feed off debris on the pond floor and other small pond organisms, making a significant contribution to the well being and equilibrium in the pond. Mussels can live for up to 12 years and the Swan Mussel can grow up to 15cm in length.
For further information on planting your aquatic plants click here