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The deep-sea dragonfish is a predator that lives deep in the Pacific Ocean. Like many other deep sea predators, it's got an oversized jaw and a bioluminescent appendage to attract prey, but it does have one weird (and strangely useful) difference: its teeth are transparent!

Thumbnail Credit: David Baillot/UC San Diego Jacobs School of Engineering

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Meet Aristostomias scintillans, a species of fish that lives in the deep, dark waters hundreds of meters beneath the Pacific. It's occasionally called the “shiny loosejaw”, because sometimes when you name a thing, you just call them like you see them.

This animal is part of the dragonfish family, and like most of its relatives, it's a creepy-looking thing with a disproportionately huge jaw; long, pointy teeth; and a bioluminescent barbel for attracting prey. But of all the dragonfish, which are wonderful, this one is special. It's tiny, usually only about fifteen centimeters long, but it's also a fierce hunter with an amazing adaptation.

To catch prey, the fish has fangs… that are transparent. Most animals' teeth are, this probably won't be surprising, not transparent. Vertebrate teeth are typically hard, calcified structures in the mouth, and although they're not quite the same, they tend to look pretty similar to bone.

They have an inner layer of what's called dentin, and an outer, hard layer called enamel. And they look opaque because they reflect, absorb, or scatter most light. This dragonfish has a much more unique situation, because its tooth composition is very different from what we see elsewhere.

Both the enamel and the dentin are made of unique mineral matrices containing nano-scale crystal rods; basically, very tiny crystals. They're even smaller than the wavelengths of light that normally hit them, which means they scatter barely any light. Instead, the light can go right through their teeth.

Additionally, these teeth also don't have dentin tubules. These are little channels that run through our teeth, and they're a major place where light gets scattered. So not having them helps this dragonfish keep its mouth crystal clear.

This is all super cool, but there's still a pretty big question here: What's the point of having clear teeth? Seems like they're working pretty hard for this, so why? Well, that comes down to the dragonfish's hunting style.

These things swim around with their mouths open, and when some unsuspecting prey gets too close, their mouths snap shut like traps. So the point of this fish's transparent teeth is to make its maw virtually undetectable to prey by not reflecting any of the dim light in the deep ocean. Combined with the dark color of its body, this gives the species a unique level of stealth as it hunts.

This fish is really cool in its own right, but there's actually something beyond just the “wow” factor here. Because researchers are also hoping to use this animal as inspiration for advancing materials science. Engineers aim to copy the nanostructure of these teeth to make transparent ceramics, which could be used for super-strong armored windows, laser housings, and other tech.

This is just one example of biomimicry, a field of engineering that aims to adapt the awesomeness of nature into useful technology. Biomimicry has led to better bullet trains based on bird beak shape, more sustainable building ventilation based on termite mounds, and much, much more. So I guess, like, never be afraid to look a gift dragonfish in the mouth!

Thanks for watching this episode of SciShow! If you have any jaw-dropping facts you think we should turn into an episode, feel free to leave us a comment! We're always on the lookout for new, amazing ideas.