The best known sense of snail certainly is their tactile sense or sense of touch. Almost everybody might once have touched a snail’s head to see it withdraw its feelers or tentacles, a movement which is amazingly fast for an animal as slow as a snail. Observing a snail moving through its natural environment this withdrawing of feelers can often be seen, as it happens any time the snail encounters an obstacle. Any of those is examined closely with the feelers before the snail moves over it.
A very interesting and spectacular experiment to test the tactile abilities of a snail is the razor test. For that you need a snail and a knife, at best a razor, but any knife will do, though a razor is of course more spectacular. To fasten the razor on the table, two lumps of plasticine or Play-Doh on either side of the handle will do fine. Then the snail is placed with its head in front of the knife, so it has to start moving of the blade. Not only will it be able to do so unharmed, but also it becomes very well visible, how it examines the blade with the tentaclesbefore moving over it. This movement of course is very much supported by the slime a snail crawls on reducing the friction between foot and surface.
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