While there are some terrestrial snails that are omnivorous and even carnivorous, most are herbivorous. Each species has a diet dependent on its size, age, habitat and individual nutritional requirements. They all must feed on foods that include significant amounts of calcium in order to keep their shell hard.
Those species that are herbivorous consume a variety of plants, including the leaves, stems, bark and fruits, as well as fungi and occasionally algae. They do so in an unusual way. Snails have an organ in their mouth with rows of tiny teeth, called a radula. When the food reaches this structure that looks like a sack, the teeth do not cut or grind it like human teeth would. Instead of being chewed, the radula scrapes the food and breaks it down before it passes through the esophagus to continue the digestion process.
The tiny teeth on the radula suffer much wear and tear as time passes. Therefore, they are continually replaced by others. Not all species have the same number of teeth. Some have rows with just a few teeth, while others have hundreds.
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