If you thought the movie JAWS  was scary, brace yourself.

There are so many other terrifying  jaws lurking in the water. Like, harpoon jaws, drill bit claw machine  jaws, skinless jaws, and so much more.

It’s nightmare fuel. But it turns out that the most bizarre jaws  in the water are pretty useful adaptations. As weird as they look, they  make those animals successful.

So come with us on this jaw-dropping  exploration of marine mouths and mandibles. [♪ INTRO] I’m gonna start this video with an animal that’s  just about as different from us as possible. Sea urchins don’t even have a proper  head, let alone a visible mouth. Their jaws are on the underside  of their bodies and look like a   claw machine from another universe.

It’s kind of like a diamond tipped  saw, with the hardest part at the tip,   and the other surfaces taking all  different shapes and densities. As they grind along, bits of what  passes for teeth flake off by design,   making them self sharpening  with the action of feeding. But, unlike a saw, those chompers are made  of calcite, which is a soft and brittle   material that doesn’t really sound like it  would be anyone’s first choice for teeth.

The thing is, they work for the kind  of eating that sea urchins need to do. These omnivores mainly scrape the algae  off rocks and make a meal of the stuff. Who knows?

Maybe with a little soy sauce, it’s not so bad. The bottom line is: sea  urchin jaws might look weird, but they’re really good at  scraping food off rocks,   which is what the sea urchins need them to do. That means some of the most intimidating jaws  on this list belong to fairly peaceful animals.

Unlike these next chompers. The Stoplight Loosejaw has a horror-film  ready face with gaunt features and huge teeth. But the piece de resistance is the fact  that their bottom jaw has no skin on it.

As in, the part of the mouth where the  tongue rests has some extra ventilation. Instead of skin, there is nothing. Just a hole in the bottom of  the mouth letting the water in.

That sounds like it would make eating harder  because food would fall out while you chew it. But the Stoplight Loosejaw uses this  almost lack of a jaw to their advantage. It allows them to close their jaw way faster.

With this adaptation, they can  chomp down in a third the time   compared to if there was any  skin there acting as a sail. And that’s really helpful when  it comes to deep sea living. Since there’s not that much food around,  they have to be able to grab what there is.

And they can’t miss any opportunity  that crosses their path. They need to do it quickly, bite off more  than they can chew, and chew it anyway. So having a bit more room, without the  restrictions of an enclosed space, comes in handy.

And not being reprimanded for chewing  with their mouths open is a nice bonus. But if you thought the  Stoplight Loosejaw was weird,   this next deep sea dweller  takes it to another level. Goblin sharks are also weird because  of their deep sea environment.

They belong to the same order as  the infamous great white shark. But they’re kind of like the  goofy, less intimidating cousin. They’re described as flabby and  not especially strong swimmers.

That has gotta hurt the ego. And since they don’t live in a prey rich  environment, they need something going for them. So what they have are jaws that shoot  out like a harpoon to catch prey, and a delicate nose that acts as a very strong  sensory organ, but for touch instead of smell.

The goblin shark paddles along in the pitch  black until it almost bumps into its prey. Then it lunges with its harpoon jaws. So they may be slow and flabby, but they have  the last laugh with their quickdraw jaws.

And don’t worry, there are no records  of human-eating goblin sharks. We’re probably too big for them anyway. But there are much larger sharks on this list.

The basking shark is the second  biggest shark in the world. And while the idea of a nine meter  shark may be a nightmare to some, basking sharks are gentle and harmless to humans. Not only do they not want to eat you, they can’t.

I know this may seem hard to believe  considering their mouths are massive   enough to engulf a human and look like  they’re lined with a ribcage, but trust me. They look like that because they  have their gills inside their mouths. And those gills are linked with structures known  as gill rakers, which work a bit like big filters.

The basking shark’s mouth is basically one giant  sieve to strain zooplankton from the water. All they have to do is swim with their  mouths open and let the rakers do the rest. So these big mouths are designed  to eat little animals, not you.

And while basking sharks may  gulp down a ton of water at once,   there’s a reason this next  animal is the king of gulping. Gulper eels, or pelican eels,   have a name that already clues you in  to what’s going on with their jaws. Like a pelican, they have a huge throat pouch  that lets them take in great gulps of water.

And the jawbone itself bends as they open their  mouths so they can do what’s called lunge feeding. Now, such a bendy jaw is not strong, and the eel  itself isn’t exactly a marine beefcake either. But they certainly get food down the hatch.

Since they’re deep sea creatures, eels  are pretty hard to watch in the wild. But researchers think they  swim slowly and function   like living nets for their fish and shrimp prey. Weird as this jaw is, researchers see it  evolving over and over again in multiple   different families, from whales to pelicans.

It may not be pretty to look  at, but it clearly works. And as the saying goes, if  it ain’t broke, don’t fix it. … Even if it gives you nightmares. Speaking of which… Ever had the nightmare of your teeth falling out?

Or even turning into corn? Well for at least one sea creature,  that’s uncomfortably close to reality. When Port Jackson sharks are full grown,   their teeth look more like a row  of sweetcorn than shark teeth.

And their jaws protrude out at the front  to put those teeth on full display. This weird configuration means the  jaws can act like a vice to both crush   shellfish and stop them from sliding  out of the mouth at the same time. But Port Jackson sharks  aren’t always this peculiar.

As juveniles, they have a more typical  shark mouth that suits their soft prey diet. They only get their hideous nutcrackers once   they fully mature and develop a  taste for hard shelled animals. But beauty is in the eye of the beholder.

After all, a fish that looks  more like us is also terrifying. Take it from this last animal. The Sheepshead fish has a mouth that  would almost look normal on a human.

But it’s a lot less normal on the face of a fish. Just like your own teeth, theirs are immensely  strong, and reinforced with several minerals. They’re especially fortified by fluoride,   the stuff you might find in  your toothpaste and tap water.

So these guys are probably the most  relatable to you or me in this video. All this means that their teeth  can take huge amounts of force,   and are proportionally tougher  than both shark and piranha teeth. So they can eat hard food.

Accordingly, molluscs and crustaceans  make up the bulk of the sheepshead diet,   especially those wedged on rocks  like barnacles and oysters. You need serious hardware to crack that food open,   and that’s how we wound up with a  fish with such a weirdly human mouth. But with that said, there are still a lot of  differences between you and a sheepshead fish,   so don’t go getting any bright ideas and  try to eat raw shellfish off the rocks.

Well, that should be enough to keep you up  for a few nights, so I’ll leave it there. As the saying goes, there’s more  than one way to crack a nut. And it seems that these underwater  animals have tried them all.

Whether they’re making up for a lack of muscle or  just trying to eat something that requires special   equipment, fish, sharks, eels, and urchins  use their weird jaws in some amazing ways. [♪ OUTRO]