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These animals can detect heat through some fascinating biological mechanisms, and they are proving to be boons to the scientific community.

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Jewel Beetles & Wildfire Detectors
Pit Vipers & Infrared Cameras
Vampire Bats & Thermogenetics

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Go to   to start streaming thousands of  documentaries and nonfiction TV shows. [♪ INTRO]. All creatures have some way of sensing infrared  radiation — the low-frequency light waves that we feel as heat.

But some dial this sense up to 11. Like, they can detect a fire from kilometers  away, or see their world with heat alone.   And these amazing critters are inspiring some super hot tech that could make our world safer and more know-able.  Most animals turn and run the other way when fire   approaches. But not some  species of jewel beetles.  They’re always on the hunt for freshly  burnt wood, because that’s the only place   their babies can develop.

So they need to be able to sense a fire from pretty far off.  At the same time, they need to distinguish  between recently burned and burning wood,   since the latter would kill them. So they have evolved some really fancy heat  sensors which help them detect fires at a   distance and determine whether something  close by is too hot or just right.  And these heat sensors are in their armpits.  Well, not really their armpits,  because beetles don’t   have arms. But they do have a pair  of pits below their middle legs.

And each pit contains around 70 dome-shaped   sensors that expand when they absorb  the energy from infrared radiation.  This expansion bends a single, very  sensitive hair inside each sensor,   which then sends a signal to the beetle’s  brain that there is a fire nearby. Even an incredibly weak signal is quickly  amplified by the number of sensors in each   pit. Which likely explains how they can  detect a fire that’s 12 kilometers away!

And these super-sensitive pits are  inspiring new types of wildfire sensors.  The goal is to make something  that works essentially the same   way — when exposed to infrared radiation, a  liquid inside a dome-shaped sensor expands,   and in turn deforms a small  membrane to send a signal. Early prototypes are not yet as  sensitive as the beetle’s pits,   but they’re inexpensive and  will only get better with time. And that’s great, because more sensitive  and affordable sensors could be a huge   improvement to our existing  wildfire early-warning systems,   especially as forest fires become more  intense and widespread due to climate change.

While the beetles might have the best  long-range fire detection in the animal kingdom,   their short-range sensing is kind of  meh when compared to certain snakes. Pit vipers get that name from the pair of  heat-sensitive pit organs below their eyes,   and they’re able to create an image out  of the infrared radiation they detect! This helps them accurately strike at  their prey — a feature especially useful   when hunting at night, when lots  of yummy small animals are active.

The pit organs work like a second pair of eyes,  except that they see heat instead of light. Each pit has a sensory membrane hanging inside   with several thousand heat-sensitive  protein channels embedded in it. And these channels are super sensitive.  They open up for temperature differences of  just a couple thousandths of a degree.

Which   is important when your prey's fur or feathers  are similar in temperature to the surroundings. When a channel opens, an electrical  signal is sent to the snake’s brain.  The pattern of signals is mapped  and processed to form an image,   much like how you and I see because our brains  can interpret signals from our retinas — though,   the snakes’ infrared image  is not as high-definition. Still, engineers are hoping to recreate  both the extreme sensitivity to heat   and the image-forming aspects of the vipers’  pits — just, without the living tissue bit.

So they’re working on developing more flexible   pyroelectric materials — substances capable  of turning a heat signal into electricity. We already have hard, crystalline  materials that do this, but developing   a supple membrane version would open  up a wider variety of applications. Like, better search and rescue robots that  can see infrared as well as the snakes!   That way, they could find people who’s heat  signature is being obscured by snow or smoke.  But not all of the tech being inspired by  infrared-sensing animals is aiming to detect heat.

What researchers are learning from  bats could teach us more about brains!  I know that this sounds like it  might be a leap, but bear with me.   You see, pit vipers are not the only vertebrates   that use infrared radiation to locate prey  — vampire bats also possess this ability! It comes in super handy for  them when it’s dinnertime,   because they feed solely on warm mammal blood. And it’s hard to do that if you can’t  tell where that blood actually is!

So, much like pit vipers, they have  heat-sensing pits in their faces.  But they use a different protein channel  — and it’s actually the same one that   humans use to detect burning hot  temperatures and spicy foods!  Typically, these channels are activated  by temperatures over 43 degrees Celsius. But inside the leaf-shaped  pits adorning their noses,   vampire bats have super-sensitive versions that  respond to temperatures around 30 degrees Celsius. And it’s those proteins that  researchers are interested in,   because they could improve upon a neuroscience  technique known as thermogenetics.

The basic idea here is that neurons are turned  on and off when ion channels open or close.  So if, thanks to genetic engineering, you give  certain neurons channels that can be opened and   closed at will, you can flip them on and off  to see what those neurons do in the brain.  Now, neuroscientists already do this with light,   as there are special channels that can be  opened or closed with certain wavelengths.  But thermogenetics aims to use infrared and  other kinds of long-wave radiation instead,   since they are able to penetrate  tissue a lot better than visible light. And that could open up whole new avenues of  study, as right now, getting the light into   the dark recesses of an animal’s brain  is, you know, tricky to say the least.  That’s why they’re excited by  the special channels in vampire   bats — they may be just the thing to  take thermogenetics to the next level!  It’s clear that, for all these animals, their  super infrared detectors are evolutionary gifts   which have allowed them to do incredible things.  And now, they’re proving to be gifts  to the scientific community as well. Speaking of gifts, if you want  to treat yourself to even more   awesome science this year, you might want to  check out today’s sponsor, CuriosityStream.

They’re a subscription-based  streaming service which offers   thousands of documentaries and nonfiction TV  shows, including exclusives and originals. For instance, if you enjoyed learning  about pit vipers and their infrared vision,   you’ll probably love The Secret Life  of Snakes. It introduces you to some of   Europe’s most exciting species through  stunning videos of their daily lives.  CuriosityStream also offers  35 expert-curated collections,   so whether you’re looking for a science-y  documentary, a quick tour of history,   or an awesome travel program,  you’ll find something for you.  You can learn more at  And if you’re interested, you can use the code   “SciShow” to sign up and get  an entire year for just $14.99! [♪ OUTRO].