Why do snails have teeth? They use their teeth to scrape away pieces of food.
Snails are not the only gastropods that have teeth. Slugs basically evolved from snails and they have teeth as well. Both slugs and snails have thousands of microscopic teeth. Depending on the size of the snail, they can have over 20,000 teeth, which puts our 32 to shame. However, their teeth are not quite the same as ours and they don’t use them in the same way.
Snails have something like a tongue that is called a radula. The radula is kept inside a sac inside the mouth of the snail, and it can be extended out when the snail is about to start eating. The thousands of teeth that snails have are lined on this radula. Snails generally have about 100 teeth in a row, and they have over a hundred rows. Some have even more teeth per row or even more rows, depending on their size. Some giant snails have been found with over 200 teeth per row and over 100,000 teeth altogether. It depends on the snail. Snail teeth are between 0.05 and 0.1 mm long and they are slightly curved. The teeth lie flat when the radula is in its sac, but they pop up when the snail extends the radula.
Snails use these thousands of teeth to eat, and they are known for eating almost anything. They are mostly detritivores, which means they eat detritus. Detritus is all of the decaying waste matter from dead plants and animals, anything that is rotting. However, different snails eat different things, and they are the scourge of many gardens because they will eat all of the plants and crops. There are even some carnivore snails which eat worms and small insects. They eat all of this food by grinding it up with their teeth. They eat in two ways. The first way is to use the radula to scrape food off surfaces, like a file. They can scrape the soft parts of food off or they can scrape things like algae off rocks. The second way is to use their radula to soften up food. They have a jaw that can cut off pieces of whatever they are eating and hold them while their radula grinds them down to be swallowed. The microscopic pieces of food are passed into the snail’s digestive tract where they are broken down. All of the snail’s internal organs are kept up inside the shell for safety, and this is where the stomach and the heart are. The snail is pretty small, so it doesn’t have a very long intestine. The teeth on the radula have to break down the food as much as possible before they eat it because they can’t break it down much afterwards.
Because their teeth grind things up, they get worn down and broken off. The snail replaces the teeth in the same way we replace our fingernails. The tooth grows up from the bottom and the top layer is replaced when it is lost.
The snail’s teeth are tiny, but they are incredibly strong for their size. Researchers analyzed their strength, and they think snail teeth could be the strongest biologically made substance on Earth. The researchers were looking at limpets, which are aquatic snails. They have a very strong muscular foot that they use to hang on to rocks. They use their radula and teeth to scrape algae off the rocks they live on. They also break off and grind up a considerable amount of the rock as well. When the researchers looked at the teeth, they found they were made of goethite nanofibers. Goethite is a mineral that consists of iron and oxide-hydroxide. The teeth had a protein matrix that was strengthened and supported by goethite nanofibers. There were far more nanofibers than protein, which makes the teeth very strong. The researchers also said that because the nanofibers were so small, they were not prone to defects which would make them weaker. The researchers tested the strength of the teeth, and they discovered that they could withstand tension of up to 6.5 gigapascals. Previously, spider’s silk was thought to be the strongest biologically produced material, but it can only withstand 1.3 gigapascals. For comparison, an 8 cm steel rope has a tensile strength of about 0.5 gigapascals. If there was a way to make an 8 cm rope out of snails’ teeth, it would be able to lift a staggering amount of weight. And this is what I learned today.
Photo by PhotoMIX Company: https://www.pexels.com/photo/brown-snail-96633/
Sources
https://www.sciencefocus.com/nature/do-snails-have-teeth
https://nhm.org/stories/microscopic-look-snail-jaws
https://en.wikipedia.org/wiki/Land_snail
https://en.wikipedia.org/wiki/Radula
https://phys.org/news/2021-03-snails-purpose-mouth-tool.html
https://www.popsci.com/snails-teeth-have-just-dethroned-spiders-silk-strongest-biological-material
https://royalsociety.org/news/2015/03/limpet-teeth-have-super-strength