Mysticeti whales don’t have any teeth at all, instead they have something called baleen.
Think of baleen as a coffee filter or a kitchen strainer (you can ask your parents to see one if you don’t know what that is – you can play with it a bit if you like to see how things like dried rice get stuck inside the strainer but water can still pass through). Baleen is a strong, but flexible material that’s made from the same protein as hair. It has lots of tiny, separate openings that perform like a filter.
Mysticeti whales take in big mouthfuls of water with their mouths open (but they don’t swallow it). Then they close their baleen plates (a part of their mouth) and push all the water back out. Because the baleen has such small openings, the water can get out but the small animals, like krill (and Pinocchio) get trapped inside. Now the whales swallow all the trapped food. Then they repeat the process (over and over again).
Some whales like the Blue, Gray, Humpback, and Right whales have baleen plates. These whales are called Mysticeti whales.
Like odontoceti whales, we have teeth -- so we know what those are. Whales are carnivores like great white sharks and wolves so like great whites and wolves all of a whale’s teeth are pointy and sharp. They use their sharp teeth for hunting their prey and for tearing flesh.