No-one needs a description of the damage that slugs can do in a garden, but the exact way in which they do the damage is quite unique. They actually do not have mouthparts as such, nor do they possess teeth as we know them. They, like most molluscs, have a radula, or rasping tongue-like organ with which they procure food. A bit of cartilage, the odontophore, forms the core of the radula. The rest of the radula consists of a band, similar to a conveyor-belt, covered with thousands of tiny tooth-like protrusions called denticles. The band moves over the odontophore, rasping away particles of food and moving them back into the slug’s gullet. The pictured slug was making short work of a mushroom.
ADDENDUM TO YESTERDAY’S POST: After several reader comments and self-reflection, I’ve come to the conclusion that yesterday’s post could well be black bear, not raccoon, vomit. While all I found in the cornfield were signs of raccoons, it was a huge field, and I may have just missed bear sign or the bear may well have visited another field prior to getting sick. The amount of vomit was so large that it would have taken a giant raccoon to have left it. Both of these animals feed voraciously in the fall in preparation for winter — black bears can double their weight prior to denning.
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Most terrestrial snails are herbivorous, feeding on a wide range of vegetation. The snail’s mouth is on the bottom of its head near the shorter pair of tentacles. Snails (and all molluscs) consume their food not with mouthparts, like insects, or teeth, like mammals, but with a rasping tongue or radula. Snails don’t bite their food, but rather, rasp or scrape it. The radula is covered with rows of tiny “toothlets” which rasp particles away from vegetation and move them back towards the snail’s gullet. Different species of snails have differently-shaped toothlets. The radula is used by the snail not only to process food, but to clean bits of dried mucus from its shell. Supposedly if you listen hard, you can actually hear a rasping sound when the latter is occurring. (If you look hard, you can just barely see the orange radula of the land snail in the photograph.)