What is a mammal? Bonus points edition.

Let’s go back to the last science class to answer today’s question. Not last last science class. Not physics or chemistry for non-science majors or forensic whatevertheelective, let’s go back to around 5th grade animal science.

What is a mammal?

A mammal is warm-blooded.

A mammal mommy produces milk for its young.

A mammal bears live young (except in Australia….of course)

That’s fine, I guess. But it’s not good enough for me, children. I am the student who demands bonus points, the finest in Lisa Frank stickers and additional pluses after my A. Let’s step up our mammal game.

For bonus points:

A mammal has true hair. Before you start imagining animals wearing wigs or merkins, think about what are considered ‘hairy’ non-mammals. Spiders and that yeti crab come to mind for me.

Children, are you ready for a new brushably soft animal companion? It's Kiwa! The Yeti Crab.

These hairs are actually “setae” which are connected to the nervous system of the animals used to sense the world around them. So remember that next time you want to really torture a spider (I’m not here to judge why), just give it a haircut.

A mammal has a four chambered heart. Fish get by with two and amphibians three. Reptiles have three or three and half chambers. And birds think they’re as good as us with four chambers. But we mammals have  sweat glands and more middle ear bones so we still win.

Stupid, panting bird. Can't even sweat.

A mammal has baby teeth and big boy teeth. Also known as milk teeth or deciduous teeth and permanent teeth, respectively.  On the last podcast, I pondered what the deal with sets of teeth was all about. We guessed correctly that other animals (polyphyodonts) just burn through multiple sets of teeth. Unlike sharks that can go through 30,000 in a lifetime, we mammals (diphyodonts) get a special hardy set of two to do all the chewing we’re so famous for.

No, it's not some little gif on loop. This is actually a 5 hour gif of a cow doing what cows do best - Nothing of interest.

Of course, there are exceptions. Elephants get up to 6 replacements. They come and go in regular intervals up until that last set, after those are worn out the elephant kind of just starves to death. Tough break. Manatees are the other exception. They get the same marching molars system to compensate a hardy diet of veggies mixed with sand.   The reptiles scoff at our puny set of molars but at least we have all kinds of tooth shapes.

A mammal is a heterodont. We have all kinds of teeth in a mouth: molars, canines, incisors, buck (although I have see buck toothed fish *shudder*) The shapes vary depending on the mammal and what a variety it is!

Like a boss.

Pretty. Pretty cool. I don’t know about you but I feel more informed about mammals.There are probably some even more advanced level mammal distinctions but I just wanted to get to the teeth.


3 comments on “What is a mammal? Bonus points edition.

  1. What is the deal with baleen plates in whales? Are they technically teeth? Do they also have multiple sets of baleen plates? Did it take me longer to ask this here than it would have taken to just AskJeeves it? Why do I use AskJeeves?

    • I actually used ChaCha because I couldn’t find a totally clear answer anywhere else. However, the ChaCha answer is self-contradictory (unless whales are not mammals): “Baleen whales are [sic] do not have teeth, they have baleen plates for filtering food from water. They work like a strainer. The largest known animal species, the Blue Whale, is a baleen whale. All mammals have teeth.Mammals have only two sets of teeth, the first set they get soon after birth, often called the ‘milk teeth’ and a larger set they acquire as an adult.” Help!

      • Well I checked with our and staff and it would appear that baleen is not considered a kind of teeth however the ancestors of whales did have true teeth. There was even a grace period where whales had both sharp teeth and baleen in one mouth and my guess is that since one virtually replaced the other, literally and in function, the word kind of stuck. So, by composition, no, they are not true teeth but function/evolution-wise? I’m gonna go with “teeth”

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