Why Sharks Are Covered In Teeth

Sharks wouldn’t be known for their fierce teeth today if it weren’t for their ancient scales.

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To learn more about this topic, start your googling with these keywords:
Dermal denticles: also called placoid scales, they’re the most primitive form of fish scales that are structurally similar to teeth and are today found only in sharks, rays, and chimaeras.
Outside-in theory: The strongest theory for the evolution of teeth, which are thought to have evolved from dermal denticle scales.
Ostracoderms: Extinct armored jawless fish that lived in the Paleozoic Era
Thelodonts: Extinct jawless fish that had individual scales as opposed to plates of armor
Placoderms: Now extinct, they were some of the first jawed fish and lived from the Silurian through the Devonian era.

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Kate Yoshida | Co-Director
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[trashbug]

So when a shark takes a bite out of another shark, that shark is simultaneously biting it back?

[le]

In short: we used to have teeth all over our body, until we started moving some of them in our mouth

[diamondjub]

The Tooth Fairy has some fancy scaly-skin boots

[marcopohl]

early fish: "I WANT THE TOOTH!"

shark: "YOU CAN'T HANDLE THE TOOTH!"

[gussnarp]

It has been a long time since I learned a science fact that blew my mind as much as this one did!

[tuckerricklefs]

2:31 WHY IS THIS SO CURSED? (MinuteEarth theory: all the stick figures secretly have a giant Pac-Man mouth full of teath, but they just keep it closed most of the time)

[AlienValkyrie]

When I first read the _original_ title, I thought it was "scales" as in the thing that measures weight, and this was gonna be about teeth measuring how hard you're biting down and making sure you're not damaging them by going too hard, or smth like that xD

[equus_ferus_caballus]

It’s amazing how sharks have all those scales and are still completely smooth

[danielled]

The Tardis was hilarious! I had to rewind/go back to see if I was imaging it.

[davidegaruti]

1:25 small sin : that seems to be a dunkleosteus, wich is a placoderm and didn't have theet, but bony blades, more like a beak, and it whent extinct leaving no descendents,

[knate]

I'm into it, but dunkleosteous (which I think was being depicted in the drawing) didn't actually have teeth as we think of them, and had boney plates that performed the same function. I'm also pretty sure the armored fish or *Arthrodira* are a separate clade from *chondrichthyes* or the cartilagenous fish like sharks.

[salakohanjanimation]

Let's appreciate this explanation of why shark covered by teeth, so now we all know about it 🙏

[VanguardJohnson]

These artworks and animations are sooo cute

[LavenderLushLuxury]

Awesome Amazing Great Science Video, MinuteEarth! I missed your YouTube Video Content SO MUCH.

[BlackSunCompany]

Nice. This is the sort of detail that's good to see.

[VictoryAsh]

Always gotta love the pokemon in there

[MaxWelton]

Seeing Mantine and Wailord in that evolutionary tree made me happy

[DracarmenWinterspring]

So are other fish scales also made of the same stuff as teeth, or did they evolve separately? Based on the order this video presents all jawed fish must have dentin scales, what's so special about sharks having them?

[bananahat]

At 1:13 you guys mention how those early fish fed by filtering through their gills, so now I’m just wondering, what’s the point of their mouths then if they don’t use them to eat? Like why had they evolved to have mouths?

[FalconFastest]

I guess you could say that teeth "tipped the scales" for vertebrates... Hahaha.... I'm sorry.