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Organisms have evolved many clever forms of armor so that they can be ready for whatever nature throws at them. And us flimsy humans can learn to enhance our armor by taking inspiration from some of these creatures, and not necessarily the ones you'd expect!

Hosted by: Hank Green

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Sources:
Gar Gloves
https://doi.org/10.1088/1748-3190/11/6/066001
https://doi.org/10.1098/rsif.2016.0595
Chiton Seeing Armor
https://pubmed.ncbi.nlm.nih.gov/31822663/
https://doi.org/10.1126/science.aad1246
Conch Helmets
https://doi.org/10.1002/adma.201700060
https://doi.org/10.1504/IJMATEI.2011.039506
Spider Vests
https://doi.org/10.3389/fmats.2020.00029
https://doi.org/10.1529/biophysj.106.089144
https://doi.org/10.1038/srep26383
http://doi.org/10.1242/bio.029249
https://doi.org/10.1073/pnas.1109420109
https://theconversation.com/why-we-cant-spin-a-silken-yarn-as-strong-as-a-spider-can-71003
Mussel Flame Retardants
https://doi.org/10.1021/acs.chemmater.5b03013
https://www.niehs.nih.gov/health/topics/agents/flame_retardants/index.cfm

Images:
https://www.mcgill.ca/newsroom/article/protective-wear-inspired-fish-scales
https://news.mit.edu/2017/conch-shells-better-helmets-body-armor-0526
https://commons.wikimedia.org/wiki/File:Alligator_gar_(Atractosteus_spatula)_I.jpg
https://www.flickr.com/photos/14405058@N08/2352343294
https://commons.wikimedia.org/wiki/File:Mineral_texture_of_ganoine_layers_in_the_scales_of_an_alligator_gar..tif
https://www.mcgill.ca/newsroom/article/protective-wear-inspired-fish-scales
https://commons.wikimedia.org/wiki/File:Tonicella-lineata.jpg
https://commons.wikimedia.org/wiki/File:Mopalia_hindsii.jpg
https://commons.wikimedia.org/wiki/File:Chitonidae_-_Chiton_squamosus.JPG
https://www.eurekalert.org/multimedia/pub/218991.php
https://www.eurekalert.org/multimedia/pub/103683.php?from=312252
https://www.eurekalert.org/multimedia/pub/103432.php
https://www.eurekalert.org/multimedia/pub/218992.php?from=449783
https://commons.wikimedia.org/wiki/File:Queen_Conch_(Lobatus_gigas).jpg
https://bio.biologists.org/content/7/2/bio029249
https://www.eurekalert.org/pub_releases/2018-10/asu-atu101518.php
https://commons.wikimedia.org/wiki/File:CornishMussels.JPG
https://commons.wikimedia.org/wiki/File:Mytilus_with_byssus.jpg
[♩INTRO].

Let’s face it: life can be tough. And that  means living things have to be tougher.

Organisms need to be ready for whatever  nature throws at them — predators,   pounding waves, my fists, you name it. I’m coming for you, bugs! That’s why evolution has led  to all sorts of clever armors.   And that’s something we humans can learn from.

Researchers are always looking  for better ways to protect   people since our natural armor is pretty flimsy. And they’re finding inspiration in  some of the strangest places — like   in bizarre freshwater fish, all  sorts of mollusks, and even spiders! But first, gars kind of look like  alligators with fins instead of legs.

This weird body plan hasn’t  changed much in 100 million   years — which is probably thanks to their scales. They aren’t your typical fish scales.  They are incredibly strong. In fact,   people have used them as arrowheads and tools.

And now, they’re inspiring  better puncture-proof gloves. You see, researchers were impressed by  just how tough the skin of these fish is. You can’t get through it to the soft, edible  parts with just any old pair of scissors.

You’re going to need tin snips or a hacksaw to  get in — that’s some hefty protection right there! Part of the reason their skin is so  tough is that the scales are coated   in a mineral compound called ganoine  which makes them hard and bone-like. But also, they overlap with  each other.

And that makes them   really great at stopping even  sharp objects from getting through. It’s this interlocking pattern that has inspired  engineers, because even though the fish are tough,   they can wiggle like—well, fish. So  their armor is strong and flexible.

Researchers have mimicked their skin   by 3D printing tiny ceramic scales  onto work gloves in the same pattern. The results were quite good—the gar-inspired  gloves were ten times more puncture   resistant than existing models, all while  maintaining a similar degree of flexibility. So they could protect people from being poked by  sharp objects while still allowing them dexterity.

And that would be a huge step up for  workers who have to sort through lots   of different materials — like those  handling our recycling and garbage. Chitons are mollusks, which means  they’re in the same major group   of living organisms as snails, clams, and oysters. And most live in the rocky intertidal  zone: the wave-swept edge of the ocean.

This is rugged terrain. In addition to the pounding of the  waves, there’s always the risk of   being left exposed to the air and  predators when the tide goes out. So of course, chitons have several different  ways to protect themselves from these threats.   But perhaps more importantly,  their armor can see what’s coming!

Their entire bodies are wrapped in a  thick leathery girdle. Think shapewear,   but for a slug, and made of muscle. This flexible sheath helps them move around on  uneven surfaces and suction tightly to the rock   if a predator or wave threatens to knock them off.

And attached to it are eight interlocking plates. All this armor protects them much in the same  way that the gar’s overlapping scales do. But it can do something the  gar’s can’t: it can see.

Their bodies are peppered with a  bunch of tiny eye-like structures. Researchers have known about these things  for a while, but up until recently,   they didn’t think they were using them for vision. That’s because the lenses of these  eyes are made of crystalized calcium   carbonate — the same protective  material as the chiton’s plate armor.

And that’s totally different from most  other animals. Lenses usually consist of   squishy proteins, because they need to bend  to focus on objects at different distances. But it turns out these hard lenses work  just fine!

Chiton eyes can sense light and   dark and even form images — they just can’t  focus those images the same way ours would. More importantly, though,   the crystal structure of the carbonate  contains multiple refractive indices. That means it can bend the light enough to  see it no matter what medium it’s traveling   through before it reaches the eye.

So their  eyes work the same in and out of the water! Having eyes all over their bodies  means chitons are able to see threats   approaching from any direction. That gives  them time to clamp down tightly as needed.

And having hundreds of eyes means their  vision isn’t interrupted if a few get damaged. Researchers want to recreate this kind  of seeing armor by 3D printing a material   that is both flexible, and impact  resistant, and incorporates vision. That way, the wearer knows what’s around them…  something which would be especially handy for   military combat or in other volatile situations,  like at the scene of a natural disaster.

They specifically want their eye-like objects  to function much like the chitons’ — to be able   to see in both air and water, and  keep working if a few get damaged. If successful, this would be the  first material of its kind — and   a huge advancement towards the  creation of multifunctional armor. Conchs are large marine snails,  with hard, spiral shells.

And though these shells are mostly made  of the same stuff as chiton plates and   other mollusk shells, they’re even stronger —  which is why engineers think they could take   helmets and other protective  equipment to the next level. Conchs need extra-tough shells  to survive their predators: like   ravenous crabs with strong pincers, and  the tough beaks of hungry sea turtles. But like their brethren, they start with  something quite brittle: calcium carbonate.

To make this mineral tougher, they combine it  with soft, wobbly proteins to form intricate,   three-tiered structures arranged  in a crisscross-y pattern. The complexity is the key here,   because it makes it so that even if  a crack forms, it doesn’t spread. Essentially, the design creates a maze  that the crack has to travel through.

This makes their shells ten times stronger than  nacre — one of nature’s strongest substances. Before the invention of 3D printing, it was  next to impossible to recreate these structures. But now, engineers have successfully printed  sheets in this same pattern, using both a   rigid and a squishy polymer to represent the  calcium carbonate and proteins used by the conch.

This 3D printed material can resist cracking,   similar to the conch’s shell, as  well as absorb energy from an impact. And they’re hoping to use it in  protective gear like sports helmets. That way, they’d be more resistant to damage  and absorb some of the energy of an impact,   which would better protect the  wearer from traumatic injuries.

They could even print customized  helmets for a perfect fit — something   not feasible now because there are too many  materials involved in manufacturing them. Anyone who’s ever walked through a spiderweb   knows that the silk that they  spin is strong and stretchy. In fact, the silks from orb-weaving   spiders often outperform the best  synthetic fibers on the market!

They’re lighter, stronger, and they retain heat  better than anything we’ve manufactured so far,   which is why some companies  have already started using   them in everyday protective items like outerwear! But now, researchers are hoping to use spider silk   as a replacement for another  strong synthetic fiber: kevlar. Kevlar is a popular choice for bulletproof vests  because it’s lightweight and extremely strong.

But researchers think spider silk  could be the key to an even lighter   and more flexible material — one that  could absorb the energy of a bullet,   but still be stretchy enough to allow  the wearer to move and bend with ease. Two proteins, aptly named spidroin 1 and  spidroin 2, form the basis of spider silk fibers. The exact strength and stretchiness of the fiber   depends on how they’re arranged  as well as what they look like.

You see, these two proteins can look  a little different in fibers from   different parts of the web, or different species. They can even vary depending  on what the spider eats! So researchers are still studying  all these small variations hoping   to figure out the best silk for stopping bullets.

Though, even the stuff we have now is  stronger and more flexible than kevlar. The real reason it hasn’t taken over the  market is that it’s tricky to mass produce. We haven’t figured out how to spin this kind of  silk in a lab, though a company in the United  .

States has genetically engineered silkworms that  produce spider silk instead of their own silk. And you might be wondering why  we don’t just farm spiders. Well, for starters, spiders sometimes eat each   other when kept in close proximity.  Which makes things a bit trickier.

Plus, you’d have to have a whole  separate farm for their prey!   Herbivores like silkworms are much easier to feed. But more importantly, spiders require a lot of  space to build their webs, while silkworms don’t. So a spider farm would make  the silk extremely expensive.

Besides, we’ve already got the  infrastructure in place for silkworms.   Worldwide, more than 150 thousand  metric tons of silk are made per year. And if it ain’t broke, don’t reinvent  the wheel, or something like that. Now as incredible as super-kevlar,  3D printed helmets, or anything else   we’ve talked about so far would  be, they have a weakness: fire.

So, to really be tougher than tough, they’d  need a little help from a flame retardant:   something that’s applied to a flammable thing,   in order to slow down how quickly  that thing will burn in a fire. Unfortunately, growing evidence suggests  that many of these chemicals are toxic   and can cause serious health issues, which  is why these products are no longer applied   to everyday clothing, even though it  could help save lives during a fire. So many people are searching for  non-toxic options for firefighters   and other workers frequently  exposed to flames or sparks.

Researchers may have found a solution, though,  in a somewhat unexpected place: mussels. I mean the small, aquatic  mollusks, not your biceps. Now, it might seem strange that a water-dwelling  animal would possess the means for stopping fires.

But they’re not using it for that.  They’re using it to stay in place. The substance is called polydopamine,   and it’s the waterproof glue that keeps  them from being swept away by rough waters. As an added bonus, researchers have discovered  that it’s also a great flame retardant — for us,   not the mussels, seeing as they  don’t experience a ton of fire.

It works by binding to molecules that  get released by a substance as it burns. These molecules, known as free radicals,  typically end up adding more fuel to   the fire because they react with other  compounds and make them more flammable. By binding to free radicals, polydopamine  slows down the speed at which the item burns.

It also generates a layer of char, that helps  to block the fire’s access to the material. And it does all this   really well. It outperforms many conventional  flame retardants on the market today.

Not only that, polydopamine sticks to just  about everything — which makes sense because   it’s a glue — so it could be applied to  anything we want to make fire resistant. Plus, it’s not toxic! This means it could be applied  to everyday wearable items,   or even the other armors on this list,  to make them safely fire-resistant.

Though, researchers are particularly interested  in using it to coat polyurethane foam,   the primary ingredient in many consumer products  like furniture, mattresses, and car seats. Thanks to these keen observations and newer   technologies like 3D printing  and genetic engineering,   we’re already well on our way to making all  kinds of futuristic, protective materials. All scientists and engineers needed was a  little inspiration to kick things up a notch.

And it’s only fitting that they’ve  gotten that from the natural world. Over millions of years, evolution has  made it so that creatures on Earth   are well defended against a  myriad of potential threats. So it’s the best engineer around — and  it always pays to learn from the best.

Thanks for watching this episode of SciShow!  And an extra thanks to all of you channel   members who support what we  do right here on YouTube. You’re a big part of how we’re able to  offer videos like this for free to everyone. So if you’re a channel member: thank you!

And if you’re not, but would also like  help us make free science education videos,   you can learn more about becoming a  member by clicking the “join” button. [♩OUTRO].