This story isn’t about floss. Not this time. It’s about the unusual variations of teeth in the animal world

I have to credit pediatric anesthetist Dr. Karen Brown for asking me one day, while we were working together in the O.R., if I knew which mammal had the largest number of sets of teeth. I failed the test because I didn’t know the answer. So Dr. Brown told me.

As most of us know, humans have 2 sets of teeth, but that’s not true for some of our friends, the animals. Not always.

It turns out that elephants grow up to 6 sets of teeth in a lifetime (the record), and that can be a long time, something like 70 years or so. It’s not like our teeth, where the permanent teeth form under the baby teeth and grow into the mouth to replace the baby teeth as they are shed. In elephants, as well as in dugongs, kangaroos (nor strictly mammals, but marsupials) and a certain type of African rodent, all have the teeth slide forward in the jaw, and as the frontmost of 3 molars are shed, new ones grow in behind them, something like a tooth assembly line. This type of dentition is called polyphyodont.

Of course, that’s not so for the elephant’s tusks, which are actually a specialized type of tooth. They’re the ones that the poachers are after, with the result that elephants are rapidly going extinct. Tusks keep on growing longer throughout the elephant’s lifespan. They’re not shed.

Now you know.