Snails
- A snail is an invertebrate that is a part of the gastropod class.
- Snails have coiled shells that they can fit completely into.
- The majority of marine gastropods breathe through a single gill, supplied with oxygen by a current of water through the mantle cavity. This current is U-shaped, so that it also flushes waste products away from the anus, which is located above the animal's head, and would otherwise cause a problem with fouling.