E. Cioran

Fig. 1: The Brown lipped snail (Cepaea nemoralis) has a surprisingly aesthetic appearance and diversity in its stripes.

The Snail The snail he lives in his hard round house, In the orchard, under the tree: Says he, „I have but a single room; But it‘s large enough for me.“
Anonymous

Fundamental aims of the activities • To discover diversity among native snails • To reduce prejudices andfeelings of disgust • To recognise the role and usefulness of snails in an ecosystem • To awaken interest in snails as examples of molluscs

Snails
Snails are very suitable for use in class because of their slow way of moving and because they are very easy to keep. They are easy to find and to observe. Most city children know something about snails, too. The starting point is therefore theimmediate environment and the direct experiences of the pupils. The aesthetic appearance and diversity of snails stands in opposition to their very low popularity. When they think of snails, many people associate them with the endless fight against the seemingly invincible slugs in their gardens. Our relationship with this interesting and extremely diverse group of animals is often reduced to that ofenemies. The cause of this is mainly the Portuguese slug, which reproduces in large numbers, and a few other slug species. An important theme of the “snail activities” is therefore awareness when dealing with other living creatures. The thoughtless treatment of snails in particular by young people should encourage us to show

Snails 

our pupils the interesting and beautiful aspects of theseanimals. This group of animals is often completely misunderstood and now endangered, and at the same time it is an example of how we are dealing with our living environment. The sole benchmark “useful” versus “useless”, from the perspective of humans, separates species into the questionable categories “worthless” and “valuable” (because they are cute or useful). Snails can cause feelings of disgustin children and young people. But if they observe them more closely and have contact with them, then curiosity and thirst for knowledge usually predominate. The pupils can discover astounding phenomena which they are able to examine themselves in simple experiments.

1. Factual information about snails
Biology of land snails Snails (Gastropoda) make up the class of animals with the most speciesfrom the phylum molluscs (Mollusca). They can live on land as well as in the water (snails and shellfish). In the following, only the biology of the land snail is described.
In land snails, oxygen intake occurs through a network of thin-walled blood vessels in the mantle cavity under the shell. Loss of water through breathing is a serious problem for snails that live on land. Protection againstloss of water is provided by a particularly thick fold of skin in the mantle which closes off the mantle cavity. The stream of air which the snail breathes in passes through a small opening called the breathing pore or pneumostome. The snail can use its muscles to control the opening of the breathing pore. Breathing takes place by opening and closing the breathing pore as well as by raising andlowering the floor of the mantle cavity, which you can compare to the use of the diaphragm in vertebrates. Many snails make use of the cool and damp conditions at night and are nocturnal. If it is too dry, they look for a suitable hiding place to wait out the dry period. Some snails crawl up plant stems and fall into a state of dormancy. They then close off the entrance to the shell with a seal madeof slime, with which they also stick themselves to the surface they have chosen. Because of their famously slow method of movement, the snail’s radius of activity is very small. The chance of meeting a partner for mating is rather low. Therefore androgyny is an advantage: they have double the chances of reproduction with a low number of individuals because the snail can reproduce with every...