Mussel (Swan)

admin — Wed, 19 Sep 2007 16:32:53 +0000

The Swan Mussel is a freshwater ‘bivalve’ mussel which means it has a soft body that is enclosed in two hinged shells. It can be found in lakes, canals and slow-flowing rivers. It buries itself in silt or mud as deep as twenty metres and it extends two ‘siphons’ which are tube-like organs that can take water in and squirt water out.

The Swan Mussel has an oval-shaped shell which is usually a brown colour with lots of darker or lighter brown curved lines. It can sometimes be a yellow-brown or an olive-brown colour. The inside of the shell is pearly white and the soft body inside is a rosy orange colour. The Swan Mussel has a large muscular foot which the mussel uses to burrow into the sand and to move along the surface. If it gets disturbed, it can quickly close both shells tightly shut.

The larvae of the Swan Mussel hatch inside the mussel during winter, but they are not released till the following spring. When they are released, they have sticky thread-like strings trailing behind them and the larvae use these strings so they can attach themselves onto fish. The larvae suck blood out of fish for a while and then eventually drop to the bottom of the water to develop into adult Swan Mussels.

Snail (Great Pond)

admin — Wed, 19 Sep 2007 16:33:55 +0000

The Great Pond Snail is the largest water snail in England and can be found throughout the country in ponds, lakes and canals with slow-flowing waters. This snail deliberately eats grains of sand which stay in its ‘gizzard’. The gizzard is the part of a stomach that grinds up food. The sand in the gizzard helps the Great Pond Snail to eat and digest tougher plant material.

The Great Pond Snail has a large cone-shaped shell on its back which can be brown, yellow-brown or grey in colour with lighter and darker line markings. The shell can be as long as seven centimetres. The soft body under the shell is a yellow-grey or a brown-orange colour. Its head is large with two tentacle-looking organs. It also has a large slimy muscular foot that helps the snail to move along surfaces. It often leaves a trail of slime wherever it goes.

The Great Pond Snail can often be seen floating upside down on the surface of the water taking in air because the opening for its lungs is on the underside. It usually eats algae and plant matter by using a tongue-like organ that has horny teeth on the surface. It also eats decaying organic matter and even small Great Pond Snails.

Freshwater Molluscs

Mussel (Swan)

Snail (Great Pond)