Interestingly, crabs do have teeth. But not in the way you’d think.
Most crabs have very soft feathery mouths, so they need a way to break up all the food they ingest. Instead of chewing and breaking up food in their mouths, they do this is their stomachs. A crab’s stomach is split into two parts – the first houses three strong teeth to grind up the food they eat, strong enough to grind up hard and gritty material, including shells. The teeth are made of exoskeleton material shaped like teeth, so a bit different to ours. The section of the stomach responsible for grinding up food is called the gastric mill. Birds also have something similar called a gizzard and it works much the same way. This style of eating was even present in some dinosaurs. Other animals that make use of a gastric mill or gizzard are: earthworms, crocodiles, alligators, some gastropods, some fish, and some crustaceans.