Dienstag, 16. April 2013

Snails with shells

Arianta arbustorum
Snails are very successful animals. They have already existed for millions of years and populate land and water. Aside from the deserts and polar areas you can find snails everywhere. These animals are important for our ecosystem but they don’t get the attention they deserve. Please read on and discover more about these amazing animals, especially about the large garden snail.

Snails belong to the Mollusca. Mussels belong to this clade too but snails are much more speciose - there are about 43’000 kinds of snails! I like our garden snails with a shell (we call it house) on their back. Depending on the type of snail that shell comes in a various shape, but all snail shells are twisted in the same direction: rightwards. Sometimes there’s a snail with a leftwards twisted shell. That’s very very rare and we call these snails “snail kings”. Oooohhh, I wish I would find such a snail or (even better) a shell of a snail king. Oh I wish it so hard!

Here some different shapes and sizes of land snail shells. You can find such shells in the garden and forest. I really like the striped one. The right one is a Alinda biplicata.
When I was a child my friends and I loved to collect snail shells. The big shells of the large garden snails were very precious to us. I still have my collected snail shells, filled in a jar. It looks decorative.
Actually snail shells are just white because they are made of chalk. But there’s a second layer, a kind of skin (periostracum) over it. This skin makes the shell colorful.

Here you can see the periostracum very well.
Snails with shells hibernate during winter. It may sound ridiculous but the large garden snail dig a little hole in the ground. The large garden snail uses a secretion to “build” a lid in order to seal its shell. This lid is called epiphragm and protects the snail from frost and dryness. It is even pervious to air so the snail can breathe though. If the snail doesn’t need the lid anymore it simply pushes it away. You can find these calciferous entities in gardens, hedges and forests as well.

Even with epiphragm some snails die during winter. Here you can see some closed shells of the large garden snail.

The “house” of a snail is an amazing thing. A muscle is connected with the shell so within a few seconds the snail retracts itself into it, safe and sound of dryness, cold, injuries and predators. If the shell of a snail is damaged, glands emit chalk which will repair the damage as good as possible.

It will survive.

Cross-section of a large garden snail shell. It’s loopy inside as well. 

Did you know that snails are hermaphrodite? There even are some snails with hair on their shell! Snails are such wondrous animals, I could write pages about them. If you get the chance buy a book about snails – it’s well worth it!

That might get a little hairy... Helicodonta obvoluta.
Cepaea nemoralis.

And last but not least: The large garden snail (Helix pomatia).

2 Kommentare:

  1. I love snails but I hate them when they eat my vegetables in my garden. Do you have some tips and advice about this problem.

    Denver patios

    1. Hi ketz!
      Yes I know your problem, but I don't know a 100% solution. Actually the slugs are more vegetable eater than the snails with shells. Maybe you have some hedgehogs arround, so you can build some "homes" for them.