The mammals that have the most teeth are dolphins. An oceanic dolphin may have up to 260 teeth on average. Each tooth is cone-shaped and approximately 0.4 inches (1 cm) in diameter. Dolphins’ teeth are evenly spaced apart and designed to interlock, which allows them to trap prey, a variety of smaller fish, in their mouths and swallow them without the need for chewing. Unlike other large sea creatures such as sharks, that have a lot of teeth, dolphins only have one set of teeth in their lifetimes. If a dolphin loses a tooth, it does not grow back, just like with human teeth.
More about dolphins:
These are some very interesting facts about dolphins, which not only shows that there's more to them than meets the eye, but even more so, that in some ways, they even have some of the same traits that humans do.
This is especially the case in the third bullet point, which talks about how dolphins never really "sleep" because they'll drown if they do. That's a very interesting tidbit, and it also shows that even though some animals are able to sleep underwater, that isn't the case for all of them.
On another note, despite their small size, I also find it interesting that dolphins eat so much. It really shows that size doesn't always matter when it comes to animals and their diet.
Overall, these are some very interesting tidbits about dolphins. Not only do they have the most teeth, but they also have some very unique traits that separates them from other sea creatures. Considering their traits, I wonder if that's why they're able to interact with humans so well.