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the animal within s01e02
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00:00Humans navigate the world with five senses, but we often forget there are many aspects
00:05of this world we can't see, hear, smell, touch, or taste. Many animals can sense far beyond
00:12our abilities, thanks to eons of evolutionary trial and error. Imagine if we could use the
00:18Earth's magnetism to get around, or if we could communicate by sensing seismic vibrations.
00:24What if we were able to hunt by detecting our prey's electricity?
00:27These incredible and highly attuned creatures have been given access to sensory inputs that
00:33humans can only dream of.
00:55When we picture elephants, one of the first features that comes to mind are its ears, whether the massive ears
01:02of the African elephant or the relatively smaller ones of their
01:05Asian counterparts. And in terms of senses, ears makes us think of hearing. But with the elephant, hearing with their
01:11ears is not the entire story.
01:13It is thought they can also listen with their feet. Engineers have even wondered whether these creatures could hold the
01:19answers to better hearing aid designs.
01:21Elephants, they're very charismatic creatures. They're the largest land mammal.
01:26They really have a vast number of different adaptations that really aren't that prevalent in the rest of the animal
01:34kingdom.
01:34Their ability to use subsonic sound to communicate and kind of act as the animal world seismometers.
01:42Conventional hearing involves the three sections of the ear working together to deliver sound to the brain.
01:48Because sound is a vibration, it moves the air around it. So when a bell is rung, the air around
01:54it moves to create sound waves,
01:56which hits the outer ear, then the middle ear, then the inner ear, before traveling to the brain.
02:01Elephants use conventional hearing all the time, yet they also seem to pick up sounds that are not in the
02:06air.
02:06For example, they can sense rumblings well before a storm.
02:10There's a lot of evidence to say that elephants pick up seismic events, whether it be a tsunami or an
02:16earthquake,
02:17long before other animals pick it up, that they start moving away or changing their behavior
02:23in response to something before humans perceive it. So this tells us that elephants have some special sensory perception
02:31to the vibrations occurring in the ground.
02:33Hearing a massive seismic event is one thing, but in the 1990s,
02:38scientists realized elephant seismic detection might be much more subtle and sophisticated.
02:43Observing the animals congregated around a drinking hole, biologists noticed a set of strange behaviors.
02:50The elephants would lean forward, pick up one leg and freeze for no apparent reason.
02:55Biologists believed they caught them in the act of picking up a vibration from the ground.
02:59The human hearing range is from 20 hertz to 20,000 hertz.
03:04So a hertz is a cycle per second, so 20 hertz would sound like a very deep bass drum.
03:11Thumb, like as deep as you can imagine.
03:13Whereas 20,000 hertz would be extremely high-pitched.
03:17Elephants are at the opposite end of the range.
03:20Elephants are only able to hear frequencies as high as 16,000 hertz and as low as 5 hertz,
03:26sounds that would be much too low for us to pick up.
03:29Elephants have much more sensitive cochlear ear components that allow them to be able to be more sensitive to these
03:36sounds.
03:37And having that wide space in between their ears allows them to really fine-tune the direction at which the
03:43sound is coming from.
03:44Elephants can also vocalize in lower frequencies.
03:47And while the elephant's high-frequency shrieks can be heard by anyone close by,
03:52their low-level vocalizations can actually travel much farther.
03:56Elephants have eight times longer vocal cords than humans have.
04:00It allows them to vibrate at lower frequencies.
04:02And with lower frequencies, they're able to transmit to the ground like relay waves.
04:07Sound travels much better through high-dense media than low-dense media.
04:11So through the air, when an elephant makes a rumbling sound, that travels maybe 9 kilometers at most, 10 kilometers.
04:19But when traveling through the ground, it's much more efficient.
04:21So it can travel 16 to 30 kilometers through the ground.
04:25In historic times when rail was common and you wanted to know if the train was coming because it was
04:31late,
04:31you'd lay down on the track and put your ear to the rail.
04:34Because of the higher density of the rail, the sound travels much more efficiently.
04:39And you can clearly hear the train's movement long before you can ever hear it through the air.
04:44So much of the elephant has to do with size.
04:47The size of its body. The huge amount of land it traverses.
04:51It was not beyond human comprehension that elephants could produce massive vibrations with their weight alone.
04:56And certainly that is part of their communication.
04:59During mating season, a female elephant will stomp on the ground
05:03to let the male elephants know she's there.
05:05And vibrations from her stomps can be picked up from a male 10 kilometers away.
05:10It's a really neat adaptation that's making use of that biology, that massive size.
05:16Amazingly, the elephant's foot might also be hearing one by way of bone conduction.
05:21While this sense might seem otherworldly, it helps to remember that one of the world's most famous composers used a
05:28similar tactic.
05:29Beethoven created some of his finest works after he had lost his hearing.
05:33By putting a rod in his mouth which tuned his piano, he used bone conduction to hear his music.
05:39When the elephant's, you know, pushing down on the ground, it's actually feeling the mechanical energy directly,
05:46rather than it going through the stages that it would in the ear.
05:49So it's more like somebody tapping on you and feeling the taps rather than actually hearing it.
05:55But how exactly does this conduction work?
05:57Like all mammals, elephants have receptors called piscinian corpuscles, or PCs, in their skin.
06:03These are hardwired to the part of the brain that processes touch and vibration.
06:08Elephants have a large amount of these PCs around the edges of their huge feet and toes.
06:13Researchers noticed that when picking up a far-off signal, elephants would press their feet into the ground,
06:19enabling them to enlarge the foot's surface by 20%.
06:22Scientists think they are able to interpret the sound either from the foot or from even the toenail.
06:28And it's through these piscinian corpuscles.
06:31And it basically takes that vibration into the brain.
06:34In other words, although the eardrum is completely bypassed, the vibration still makes it to the brain's hearing center.
06:42One could argue that this is feeling versus hearing, but those two concepts overlap due to their common basis in
06:48vibration.
06:49For elephants, this has vast implications.
06:51It really looks like elephants have the ability to communicate over longer distance and warn other groups of elephants that
07:00something's happening,
07:01or provide some type of communication between groups.
07:04Especially in Africa, trucks, poachers, that sort of thing.
07:08If you hear the sounds of jeeps coming and you need to get out of the way,
07:13or you need to tell your herd to get out of the way, it actually has such an advantage to
07:17avoid predators.
07:17The elephant's extrasensory ability to communicate through seismology has not only contributed to its success as a species,
07:24but has also inspired human technologies such as hearing aids that work via bone conduction rather than amplification.
07:31Soldiers now use bone conduction to hear in specially designed headsets integrated into their helmets.
07:37Even divers have felt the trickle-down effect of elephant seismology research.
07:42New devices can be attached to diving goggles and pressed against the diver's head to relay messages from a diving
07:48partner via bone conduction.
07:50As elephants use their feet to hear and possibly talk, in the skies above, another amazing creature uses a completely
07:57different sixth sense to hunt down its dinner in the dark.
08:01There's not much truth in the old saying, blind as a bat.
08:05Not only can these animals see very well with their eyes when there's light, but they also have a way
08:09of seeing in the dark.
08:11Could bats give us the answers to more sensitive vehicles and flying machines of our own?
08:16What the bat's doing with echolocation has been something that mankind has been trying to do for decades.
08:22It is now just approaching to be able to do with autonomous driving vehicles.
08:27Basically, those vehicles have to build an image of the space around them and understand their space.
08:34Witnessing a colony of bats leave their cave is like seeing traffic at rush hour.
08:39Except, since most bats are nocturnal, this usually happens in the dark of night.
08:44Hundreds or more of bats all usher out of the same space at the same time.
08:48They move in a much more erratic darting fashion than birds, yet they never crush into each other.
08:54There's no way that we would be able to create something that operates at the speed and accuracy and detail
09:01of what a bat can do with echolocation.
09:03Imagine trying to run a ship through a complicated landscape, like a reef system, and you're using sonar, and you're
09:11going incredibly quickly and maneuvering around.
09:14Like, it just wouldn't be possible with what we're able to do. We just know that bats do it better.
09:18Even more remarkable is how bats use echolocation to find and eat their prey.
09:23When it comes to hunting at night, bats are virtuosos.
09:26Given how small and quick the bugs they hunt are, they have developed an exquisite way to outsmart their prey
09:32and not become prey to other animals in the meantime, their solution is to use clicks and echoes, nature's version
09:38of sonar.
09:39They're doing this high-speed chase in midair in the dark in a completely different way than we can imagine.
09:45For scientists and engineers, this creature has been a never-ending source of inspiration.
09:50For example, as unmanned vehicles become smaller, such as delivery drones, designers once again look to bats for clues.
09:59What biology has developed and perfected over millions of years, the ability to do echolocation continuously, regularly,
10:08and be something that the bat doesn't even have to think about is absolutely amazing.
10:12Bats are a mammal and make up a staggering one-fifth of the world's mammal population.
10:17More than 1,300 bat species are distributed across six continents.
10:21They have a patagium, which is between their body, their hands, and their fingers, which is just a membrane of
10:28skin that they use for flight.
10:30They're actually the only mammal that has evolved to fly.
10:33Researchers believe bats descended from a tree-dwelling creature that had no wings and jumped from tree to tree.
10:39Then, a mutation caused one of these creatures to have slightly more skin under its arm, which made gliding between
10:45trees easier.
10:46Natural selection allowed this skin to be transformed into wings.
10:50This, and the bat's ability to echolocate, make it a formidable animal.
10:55But how does echolocation work?
10:57The process begins with the bat making a sound by contracting its larynx or voice box,
11:02although a few species make it by actually clicking their tongues.
11:05Think about it. It's not just trying to make noise just for the sake of making noise.
11:08It's making noise to get the information on its environment.
11:12And what happens is the sound travels a specific distance, bounces off an object, comes back,
11:17and they're able to sort of piece that picture together as they go along.
11:21A simple way to visualize this is to think of yelling in a canyon
11:24and having your voice echo back to you after bouncing off a canyon wall.
11:28But unlike the canyon analogy, the bat is flying while it calls out.
11:32There are sometimes, like, hundreds of bats in a colony, so that echolocation,
11:36you've got to be able to figure out what's around you and be able to detect what's around you,
11:40whether that's friendly or not friendly, or potential food.
11:45You know, so there's a lot of information going back.
11:46Even when you're out at night and you listen, and there are bats in the air,
11:51you listen to the sounds, it's never just one click.
11:54It's a series of clicks, and it's just that animal taking in all that information.
11:58Although we can hear some of these clicks, most of them are actually ultrasonic.
12:02Echolocation calls usually range in frequency from 20 to 200 kilohertz.
12:07Within this range, they combine low and high-frequency sounds.
12:11The high-frequency sound has a limited distance that it travels,
12:14but it gives very good resolution.
12:16So if you're trying to catch a moth in midair,
12:19that high-frequency sound is really going to allow you to focus in on the direction,
12:24the size, and the speed of that moth.
12:26The lower frequencies can't pack as much information, but they can travel further out.
12:31The low-frequency sound gives you a broader image of the space around you,
12:36so that's building the map of the trees and the landscape.
12:40Added to the complexity of this mapping is the fact that the main targets
12:44of the bat's echolocation, its dinner, are also moving.
12:47So it must also use what we call the Doppler effect to compute incoming information.
12:52So the Doppler effect says that if something's moving away from you or towards you,
12:58the frequency of the reflected wave will change in pitch.
13:02This is most apparent in a train whistle.
13:05So if the train is travelling towards you, you'll hear a very high pitch.
13:10You'll hear ee, and as the train passes, it will switch to low pitch.
13:14So it'll go ee, as the train goes by.
13:17And that's the Doppler effect, the apparent change in the frequency of the sound
13:22due to the motion of the object.
13:24And bats are going to do the same thing,
13:26so when they hear the pitch of the returning echoes change,
13:30they know not only their speed, but if the object is moving relative to them.
13:36So they're able to kind of stealth attack a lot of these creatures
13:40because these bats can essentially see or feel in the dark where they are.
13:44They're not being detected by their prey.
13:46They're just detecting their prey. It's a one-way relationship.
13:49And this ability helps, making them the ultimate nocturnal predator
13:53when it comes to catching bugs.
13:55They can catch more than a thousand insects an hour.
13:57Think about the processing time that it's doing
14:01by sending out that eco-location and eating that many insects.
14:05Engineers still dream of being able to pull off
14:08such intricate mapping mechanics with the efficiency of a bat.
14:11In terms of decibels, the sounds range from 50 to 120 decibels,
14:16which is louder than a smoke detector detonating 10 centimeters from your ear.
14:20It's even too loud for the bats themselves,
14:23and they've developed another adaptation to deal with this.
14:27Incredibly, their middle ear muscle contracts six milliseconds
14:30before the click is emitted and relaxes two to eight milliseconds after,
14:34at which point the ear is ready to receive the echo of an insect
14:38as close as one meter away.
14:40They evolved so as to not deafen themselves,
14:43but still allowing them to hear back the echoes.
14:45And their outer ear contains folds that they can tell
14:47which level of vertical position that item may be
14:50or how large it may be as well.
14:52Like their brains, bat ears are also exceptionally well-tuned
14:56into their own frequencies.
14:58Each ear has thousands of hair cells that help them with this.
15:01They can read a frequency change as subtle as one ten-thousandth of a kilohertz.
15:06When you do seismic surveys, say, in the ocean,
15:08you put sound into the bottom of the ocean,
15:10you wait for that sound to come back up,
15:12the interpretation of that information that comes back
15:14is done through an algorithm.
15:16You have a number of very high-powered computers
15:18that will process that algorithm as they move
15:21and they'll be able to take a picture fairly quickly.
15:25When you think about echolocation in the bat, it's the same thing.
15:29They're actually processing that algorithm
15:31and they're able to interpret that at a very, very fast pace.
15:35And they have to make it very fast because that animal's going to move.
15:38The fact that their echolocation sense is so refined
15:41is what makes humans think they might not need sight.
15:44Contrary to the saying, blind as a bat,
15:46they do have excellent vision that they can use.
15:49They just hide at night to be able to see those things that may be hidden.
15:53It's interesting that in the course of human history,
15:55we couldn't conceive of an animal that could see great in the day,
15:59you know, using light with their eyes in the same way that we do,
16:01and then also see in the dark using this completely new sense.
16:04Another faulty assumption humans make about bats
16:07is that their wings are like bird wings.
16:09The whole structure of a bat is really fascinating.
16:12So rather than, you know, a bird for instance,
16:16which has this kind of outstretched arm and hand
16:18and feathers are attached to it,
16:20a bat actually is like a really short arm and an enormous hand.
16:23So really their wings are just these enormous hands
16:26that they just kind of like are constantly clapping and flying around.
16:30And they use more of their body in kind of the creation of draft too,
16:35because their wings are often connected all the way to their legs.
16:38So it's really like a full body mechanism.
16:40The patagium membrane these wings are made of also makes them extra flexible,
16:45enhancing the bat's ability to glide and quickly change shape when it needs to weave and dive.
16:50While a bat's flight might not look as graceful as a bird's,
16:53it is perfect for catching 1,000 mosquitoes an hour.
16:56If you ever watch a bat hunting, it's moving all over the place.
17:00Especially if it's feeding, it's finding out that pattern
17:02and trying to figure out where that animal is.
17:04Not only has bat echolocation inspired engineers to better develop sonar and unmanned vehicles,
17:10but recently the phenomenon has been employed by neuroscience to fascinating results.
17:15In 2019, research was conducted on visually impaired people
17:19who had learned to use echoes to map their surroundings.
17:22It was discovered that the same area of the brain responsible for interpreting light
17:26was being adopted for mapping spatial locations through sound.
17:31Echolocation for the bat is not the only time evolution has bestowed a species
17:35with a special sense to hunt in the dark.
17:37A stranger example of this can be found down under.
17:41Australia is famous for its animals, from kangaroos to koala bears
17:46to probably the most bizarre creature, the platypus,
17:49which can only be found in the freshwater areas of Tasmania and Australia's coasts.
17:55It possesses one of the most extraordinary extrasensory abilities in the animal kingdom.
18:00My first thought of a platypus is that it really doesn't fit with a lot of the other species on
18:10the face of the planet.
18:12It's sort of like a mammal and sort of like a reptile or bird and sort of like nothing at
18:19all.
18:19A platypus is nature's oddball. There's no doubt about that.
18:23It's got the mouth of a duck, the tail of a beaver, it's got claws, it's got webbed feet.
18:30It just looks like somebody sewed a number of animals together to make one animal.
18:35In fact, the first European naturalist to come across it in the late 1700s thought it was sewn together,
18:42and they searched for stitches on the animal, which they assumed some taxidermist had Frankensteined together.
18:48This funny little creature has been generating confusion ever since.
18:53Given that it lays eggs and has the ability to produce venom, many originally thought it to be a reptile.
18:59It is a mammal. Mammals are defined as species that have hair and mammary glands specifically, and these animals have
19:07that.
19:08They are one of only two mammals on earth to lay eggs.
19:11But of all the platypus' bizarre evolutionary distinctions, and there are many, the most remarkable is the creature's special ability
19:18to find prey.
19:20It is something that has gripped scientists, especially those working in biomimicry.
19:24For example, in fields like prosthetics, could replicating the platypus' sixth sense help design the perfect prosthetic limb?
19:32To better understand how this puzzling creature developed its remarkable senses, we have to look to its habitat.
19:38It somehow manages to catch its prey in murky waters.
19:42As soon as the platypus goes underwater, folds in its skin, cover its eyes and ears, and its nostrils close
19:48up completely.
19:49Essentially can't see, can't use any of those senses, so how does a platypus actually detect its prey?
19:54They can only remain underwater for two minutes, and they are bottom feeders.
19:59When they detect shellfish, worms, larva, and insects, they open their mouths and catch the prey in their cheeks,
20:05then ingest them once they return to the surface.
20:08In order to score their dinner in the limited time they can hold their breath,
20:12they tend to forage in shallow bodies of water between 3 and 16 feet deep.
20:16So if you think about where a platypus lives around rivers and streams, these streams are murky,
20:22and they're also a mammal that breathes air, so hunting has to be efficient.
20:27With neither vision, nor smell, nor sound at its disposal, one might think this animal keeps hunting to a minimum,
20:34quite the opposite.
20:36They're effective hunters and can eat almost 50% of their body mass when hunting, which can last about 10
20:41to 12 hours.
20:42In order to pull this off, nature has engineered something of a superpower in the platypus,
20:48a vast and intricate system of receptors on their bill.
20:51The two receptors that they have on their bill are mechanoreceptors and electroreceptors.
20:56They have about 60,000 mechanoreceptors and also 40,000 electroreceptors.
21:01Both receptors work together to find their prey.
21:04The receptors are found in mucousy stripes on the upper and lower surfaces of the bill.
21:09They weren't fully discovered until the latter part of the 20th century,
21:12when scientists took a closer look at what they thought were relatively insignificant tiny pores.
21:17The first and more numerous mechanoreceptors each contain a simple pushrod device that triggers a nerve when pressed.
21:24Mechanoreceptors detect pressure and motions in the water. This could be generated by the prey themselves.
21:30While the mechanoreceptors feel pressure changes in the water,
21:33the electroreceptors pick up minute electrical impulses generated by the muscle activity and heartbeat of the prey.
21:40It's actually detecting electrical fields, so organisms that have a nervous system.
21:45It's an electrochemical system that produces very small amounts of electricity.
21:50And if you have a sensitive enough instrument, you can detect those electrical impulses.
21:54One analogy for this dual system is using thunder and lightning to anticipate a storm.
22:00The disturbance ripples of the water are like thunder, while the electrical pulses from the prey's muscles are like lightning.
22:07Together, these two types of signals travel to the platypus's brain,
22:11where a sonar-like image is created of the riverbed and any creatures within.
22:16So as it's moving through the water, if a small animal or crustacean moves,
22:20it can detect those electrical impulses and hone in on them.
22:23And then if it gets close enough, using the tactile sensors, grab and capture that food source.
22:29The large surface area of the bill makes it the perfect navigational tool,
22:33as the platypus waves it from side to side, orienting the receptor stripes towards its target.
22:39There's competition or threats that could be found in the area using these receptors.
22:43As they swim around, they're able to feel the pulses that can come back to them
22:47and see if they're moving in the right direction.
22:49As quirky as the appearance of the platypus, the sixth sense contained in its bill
22:54is what this animal owes its current success to.
22:57If you're underwater, you're not as exposed, you're in murky water,
23:00and you have that ability to detect prey in that murky water,
23:03you're at a pretty big advantage right now.
23:05We don't, as humans, have any direct sensors of electricity.
23:09It's just not part of our sensory system to detect electrical fields particularly strongly.
23:15Platypus is, on the other hand, sensitive enough to pick up the tiny electrical impulses in their prey.
23:21So it's an extremely sensitive instrument that really is very far outside of the human understanding of electricity.
23:29Studying platypus' superpower could give us clues to advanced sixth sense technology,
23:35such as collision avoidance in vehicles or virtual worlds in video games.
23:40Our bodies don't know how to interpret direct electrical signals,
23:45and there's no natural pathway for that.
23:48So it's very hard to build a brain-machine interface.
23:53So there's a lot of research going into how to make those connections work,
23:57because if I want a biomechanical limb to replace a severed hand,
24:03I need to be able to interpret the signals coming from the brain and cause the digits to move.
24:09The platypus inspires designers for having figured this out.
24:13One of the Earth's greatest survivors,
24:15some fossils suggest that this unorthodox little creature has been around for 110 million years.
24:21It is thought to be the last remaining member of the Ornithorhynchidae family,
24:25the earliest offshoot of the mammalian lineage.
24:28Yet we didn't begin to understand the secrets of its success until the 1990s.
24:32This is why it's really important as a human species to maintain diversity in systems,
24:38is to protect animals around the world.
24:42Because you never know what a researcher or what a scientist or what somebody will discover,
24:46you know, about a particular animal that might have a human application.
24:51These animals have honed in on these skills to survive,
24:54and so if we're able to harness those sort of honed-in tools to use for ourselves, now we're talking.
25:02While we might never have thought to do something so bizarre with our noses as the platypus does,
25:07many of us have imagined being able to see in the infrared spectrum.
25:11The advances we've made in infrared camera technology in the past few decades have been impressive,
25:16but what if we had this built right into our biology?
25:19Again, this might sound like science fiction for us,
25:22but for the pit viper, after millions of years of evolution, it takes infrared vision for granted.
25:28It really kind of puts the pit viper on the same level as a character like the predator.
25:34It's a perfect machine in terms of how it is able to detect its prey.
25:39It's sleek, it's quiet.
25:41The pit viper, including rattlesnakes and lanceheads,
25:44are a group of 151 snakes whose habitat ranges from deserts to rainforests.
25:50They are apex predators who prefer warm-blooded prey and who prefer to hunt at night.
25:55If you're looking at, you know, a warm body on a relatively cool background,
26:01the contrast is huge.
26:03You're really going to be able to see it and figure out where it is.
26:06Especially at night, the optical spectrum, the spectrum we use to see,
26:11you can almost see nothing.
26:12But in the infrared range, you have a vast amount of information.
26:16So if you have an exotherm, an animal that is producing heat as part of its biology,
26:22all of a sudden that heat becomes apparent because it's emitting infrared energy.
26:27Infrared light is an electromagnetic radiation with wavelengths longer than those of visible light.
26:33Therefore, it is generally not visible to the human eye.
26:36What gives this snake its infrared vision is the incredible organ it is named after,
26:41the pit organ.
26:42The snake has two of these, which are essentially cavities on either side of its head,
26:47about one millimeter wide.
26:49So this pit organ sits below their eyes, just above the nostrils,
26:53and essentially it has a membrane that has more than 1,600 receptor cells.
26:58These cells are attached to the endings of nerves.
27:01These nerve cells are what send the snake's brain signals about its prey's temperature.
27:06Thermal cameras have microbillometers that are able to assign a color for each pixel
27:12that they recognize based on its temperature.
27:14And it's similar to the way that the pit organs of the pit vipers
27:17are connected to their somatosensory organ system,
27:21which relates to touch, pain, and temperature.
27:24So once heat is detected, it activates and then sends signals to the brain
27:29where they can then interpret that heat signal.
27:32So the more sensory cells you have along that membrane,
27:36the more accurate the picture is, even the distance of their prey.
27:39They can sense animals probably about a meter away.
27:43I mean, that's such a helpful thing for a viper who's hunting at night.
27:47One only has to look at the potential predators the pit viper faces
27:51to see how heat sensing has helped it survive and thrive.
27:55But how detailed a picture can the pit viper conjure?
27:58It's quite blurry, so what's important is they look at the edges of that object
28:03that they're looking at, of where the heat is being emitted from,
28:06and that's how they can actually target where to aim for.
28:09When it goes to look for the mouse, with the pinhole,
28:13it basically gives it a more pointed direction,
28:16no heat, no heat, no heat, heat, I want to go this way.
28:19So it kind of acts as a focusing mechanism.
28:23The fact that the heat image lacks dimensional and spatial detail
28:26would make this trait less of an advantage
28:29if the pit viper were not already such a finely tuned predator without it.
28:33It already has good sight and hearing, and when it strikes,
28:36it does so with extreme velocity.
28:39Africa's puff adder can strike in a quarter of a second.
28:41It's super fast, it's lightning fast almost.
28:45They have to do it that fast because they're ambush predators.
28:48They'll oftentimes just sit and waiting,
28:50wait till an animal passes by or prey passes by,
28:52and they'll come out and they'll strike,
28:54putting their fangs, long fangs into them.
28:56They can actually open their mouths 180 degrees
28:59and just sort of open it to the point
29:02where it almost looks like it's dislocated
29:04and just bring in that prey.
29:06Being that they're venomous, they have solenoglyphous fangs.
29:10These types of fangs are the ones that can retract
29:13and fold over the roof of their mouth.
29:16And because it can fold over,
29:17this group of snakes can have the longest fangs in the world.
29:21And because of this, they have an excellent delivery of venom.
29:24Crowning all its other adaptations,
29:26the pit organ is like the trump card
29:28in this animal's exquisite predatory equipment.
29:31And while other animals possess infrared vision to some degree,
29:35the pit viper is the ultimate when it comes to this sixth sense.
29:38Recently, research in the Messel fossil pit in Germany
29:41turned up a fascinating discovery on the pit organ's evolution.
29:45It was found in snakes that preyed only on cold-blooded animals,
29:49like crocodiles and lizards,
29:50rather than warm-blooded rodents which were less abundant.
29:53The pit organs in these ancient snakes were less pronounced.
29:56A long time ago, they targeted cold-blooded animals,
29:59but as they began to eat more warm-blooded animals,
30:02that's when this feature became more useful
30:04because they were able to detect it better in their environment.
30:07It suggests that the organ evolved as a response
30:10to the increased availability of warm-blooded prey.
30:13The animal kingdom has taken advantage
30:15of so many different physical phenomena,
30:19and this is just yet another one looking in the infrared range
30:22because it gives such an advantage to those snakes.
30:26You can't ask for a better predator than that.
30:29I mean, it's successful for a reason.
30:31Infrared cameras give us a reference
30:33for what the pit viper might be up to,
30:35but another animal stalking the northern hemisphere
30:37uses an extra sense that we humans can hardly wrap our heads around.
30:41The red fox, a solitary expert hunter, and it has to be.
30:46The northern hemisphere where the fox resides
30:48is home to abundant prey,
30:49but these animals are quite fast and agile themselves.
30:53The fox makes use of hyper-acute senses to track and kill prey,
30:57from extremely sensitive ears to eyes that see at night.
31:01The fox is well-equipped,
31:02but it also has one unique skill that we can't even perceive.
31:06It can sense the Earth's magnetic field.
31:09When you look at how it hunts using sound and magnetic field
31:14as a combination to triangulate an actual location of a small rodent,
31:20but it's an ultra-efficient predator.
31:22The fact they create a map other than their own visual system,
31:26almost like an additional feature,
31:27like wearing, like, a set of another magnetic goggles,
31:31but it's just ingrained in them,
31:32is what makes them such excellent hunters.
31:35But how does this extraordinary sense work?
31:37How can a creature use a force such as a magnetic field?
31:41Biology blows my mind,
31:42but being able to use a sense that's so far out of our perception
31:48is just amazing to me.
31:49I can hear echolocation,
31:51so I have a perception of what a bat's doing using echolocation
31:55because I kind of have a sense of that.
31:58But with respect to the fox,
32:00I have no perception of what the Earth's magnetic field looks like,
32:04and the fox very well may have...
32:06While we have long understood the fox's evolutionary advantages in hearing,
32:11as well as vision to help it hunt,
32:12it was only in 2010 that scientists realized
32:15there may be something else at play.
32:18Observing red foxes as they hunted rodents under the snow,
32:21or hidden in long grass,
32:23scientists noticed that their success rate improved drastically
32:26when the fox was facing a northeast direction.
32:29Attacking from this angle,
32:31foxes were successful 75% of the time,
32:34versus a hit rate of only about 20% from other directions.
32:38This was the case regardless of time of day, season, cloud cover, or wind direction.
32:43I mean, that is just unreal to understand how these animals learn that behavior
32:48just by saying, okay, here's magnetic north, you know, how do you understand that?
32:53That's an algorithm that works almost subconsciously
32:57that allows this animal to just, boom, just pop on that prey.
33:01The fox may be using a geomagnetic sense.
33:04As the fox creeps towards the rodent sound in the distance,
33:08it waits for that sweet spot where the angle of the sound hitting its ears
33:11lines up with the slope of the Earth's magnetic field.
33:15At that point, the fox knows it is a fixed distance away from its prey,
33:19and it knows exactly how far it needs to pounce.
33:22It's really quite amazing to see how high they can pounce.
33:25Sensing the Earth's magnetic field is called magnetoreception.
33:29Although we know that other animals use this for navigation,
33:32such as migratory birds,
33:34the red fox is the first animal known to use magnetoreception to hunt.
33:38A lot of people don't even think of the Earth's magnetic fields.
33:41The fact that these animals are able to use that to their advantage
33:44must have evolved from millions of years.
33:48The secret is thought to be in cryptochromes,
33:50proteins in the fox's retina.
33:52Cryptochromes are very old in evolutionary terms.
33:55They exist in all kingdoms of life, including humans.
33:58Sensitive to blue light, these proteins sit on the retina
34:02and help mediate circadian rhythms.
34:03Cryptochromes are essentially photoreceptors that,
34:07and for humans, it tells us when to wake up and when to go to sleep.
34:11But for foxes, it actually has a different meaning.
34:15Recent science suggests that cryptochromes
34:17also have a sensitivity to the Earth's magnetic field.
34:20It's possible that, thanks to cryptochromes,
34:23foxes may actually see the magnetic north as a shadowy ring,
34:27much like how we think birds see this shadowy ring as they navigate.
34:30For foxes, this additional sense would act like a rangefinder,
34:34making their blind jumps more accurate.
34:37The magnetic field is telling me, as a fox,
34:40what's my angle to the object?
34:42How am I oriented with respect to it?
34:45How am I going to come down exactly where I need to come down?
34:50So the senses as a whole are building a brain map
34:54of where that creature is
34:56and how I'm going to get to that creature
34:58to make sure I'm landing directly on it.
35:00You can see how useful it would be
35:02because they need to do this really minute mapping out
35:07of how far away creatures are.
35:10And because they are pounce hunters,
35:11they have to be incredibly accurate.
35:13And if they're off by a millimeter,
35:14well, then they were completely unsuccessful
35:16and they have to try again.
35:17What's even more astounding about the fox's ability
35:20to sense the Earth's magnetism
35:21is that it's based on something that is always in flux.
35:25The Earth's magnetic field changes continuously.
35:27It flips every so often
35:29and the angle is constantly shifting.
35:31So it's amazing that these creatures, birds, red foxes,
35:34have created abilities around this continuously shifting baseline
35:39because they have to shift how they use that sense continuously as well.
35:44This isn't something that's foreign to engineers and scientists.
35:47We do use it.
35:48Prior to the advent of GPS satellites,
35:51we used autopilot that followed the Earth's magnetic field.
35:56Most cars that you buy nowadays have a built-in compass
35:59that will tell you where north, south, east, west is.
36:02We can probably tell you where on the Earth you are
36:04and your angular relationship to the surface,
36:07but we're not going to be able to have that triangulation capability
36:12that the fox has.
36:13Of course, our increased reliance on GPS technology
36:15suggests we would not trade in our cell phones for magnetic intuition.
36:19But it's fascinating to think we may have an additional super sense
36:22that we're not even aware of.
36:24As for the red fox, magnetoreception could be what gives it its evolutionary edge.
36:29Far from being at risk as a species,
36:31it is one of the most widely distributed carnivores on Earth.
36:34And more than likely, its super sense is part of that success.
36:38While the red fox uses the magnetic field to find food,
36:42it is thought that another incredible creature uses magnetoreception to find home.
36:46In 2019, scientists at the California Institute of Technology
36:51made a startling discovery.
36:53They found that humans may be able to sense the Earth's magnetic field
36:56via tiny crystals of iron in their brains.
36:59This opens up vast possibilities,
37:02the most impressive of which may be far from any high-tech labs
37:06swimming in the oceans.
37:08The sea turtle is one of those iconic species that everybody loves.
37:12It's when you see them in person, you are mesmerized.
37:15And I've human-dived with them many times.
37:17You just get this sense of wonder and awe when you see them.
37:21Sea turtles are an ancient species.
37:24They've been around for about 110 million years,
37:27since the time of the dinosaurs,
37:29which is even more incredible,
37:31given that fewer than 0.1% of every sea turtle hatchling survives.
37:35You have 200 to 400 hatchlings,
37:38and only one or two will survive to adulthood.
37:41You just look at how treacherous that life cycle is from hatchling to adulthood.
37:46From the moment its egg is laid, this life form must fend for itself.
37:50The mother sea turtle will actually dig out a hole, lay her eggs,
37:54and then go back out to sea, never to see the hatchlings again.
37:58There are many reasons for the high death rate of her progeny.
38:01They're small, and they're vulnerable.
38:03They have no real way to fight off any type of predator.
38:06Immediately upon hatching,
38:07the turtles follow the moonlight into the safer waters out at sea.
38:11But because their shells are soft at first,
38:13they remain vulnerable to sea predators as well.
38:17However, if it can make it to harder-shelled adulthood,
38:20the sea turtle can live longer than we can.
38:22Turtles can live 70 to 100 years,
38:25depending on the chances that they have in life.
38:27Today, largely due to human impact,
38:30six of the seven sea turtle species are endangered or face extinction.
38:34But in evolutionary time, this is a highly successful survivor.
38:38And the key to its success?
38:40A navigational wizardry that is based on sensing the Earth's magnetism.
38:45Sea turtles, they're able to migrate back to within feet
38:49of where they were born, which is absolutely astonishing to me.
38:53If I had that sense as a human, I would never get lost.
38:56Sea turtles seem to know exactly where they're going
38:59from the moment they're born.
39:00At birth, they head into the ocean,
39:02where they can grow up in relative safety.
39:05Then, when they reach sexual maturity at about 10 to 15 years old,
39:08the females return to the beaches they were born on to lay eggs,
39:12then immediately go back to the sea,
39:14only to return to the same beach for egg-laying every year thereafter.
39:18They go out as tiny little sea turtles.
39:20They leave this beach not much bigger than a hockey puck.
39:23They don't come back until they're mature adults to lay eggs for the first time.
39:27So they've gone, you know, if we're talking something about a leatherback,
39:31something that's, you know, a couple inches in diameter,
39:33to something that's almost car-sized.
39:36They haven't been back to that beach or even to that area possibly for decades.
39:41So this is a really amazing feat.
39:44It's not just that getting back is amazing.
39:47It's amazing that for such a long period,
39:50they can maintain a memory of this point on the Earth.
39:54Considering the vast distances of ocean the turtle travels,
39:58and depths at which it swims,
40:00it is inconceivable that it could solely be relying on such cues as landmarks,
40:04or current changes, or even stars.
40:06In February 2020, we saw a sea turtle go from Australia to Angola and back.
40:12You know, a 22,000-kilometer trip.
40:14And it's just amazing how far these animals can travel.
40:17So how do they pull off such staggering feats of navigation?
40:20They seem to be a swimming, breathing compass,
40:23constantly reacting and referring to the Earth's magnetism.
40:26Sea turtles are believed to rely on these magnetic signatures
40:29that is ingrained in them when they're born.
40:32It's believed that they have the magnetoreception
40:34that allows them to use the Earth's magnetic fields
40:38to know the direction where they're heading to.
40:41The concept of magnetoreception,
40:43or being able to sense the Earth's magnetic field, is twofold.
40:47First, there is the source.
40:49The Earth is a giant magnet.
40:51The iron core of the Earth rotates,
40:54giving rise to our magnetic field.
40:56That magnetism is pervasive.
40:58It doesn't matter whether I'm standing on the surface of the planet
41:01or 50 feet underwater.
41:03Every location on Earth has its own magnetic signature
41:07that is as accurate as a GPS coordinate.
41:10As well as the source of electromagnetism,
41:12there is the means of detecting that source.
41:15In other animals known to be magnetoreceptive,
41:18such as the red fox and some migratory birds,
41:21the means of detection seems to be by way
41:23of cryptochrome proteins on their retinas.
41:25But these require a lot of light,
41:28which is not always available to the deep-swimming sea turtle.
41:30Rather, it is thought that the turtle senses the Earth's magnetism
41:34via crystals of magnetite in its receptor cells.
41:38Magnetite is a mineral form of iron,
41:40and is the most magnetic of Earth's naturally occurring minerals.
41:43Magnetite crystals can be found at the cellular level of different animals,
41:49but because magnetic fields can be detected just like by passing through us,
41:53it's hard to pinpoint exactly where in that body those crystals can be found.
41:58Given that the research on humans at Caltech suggested magnetite response in the brain,
42:03it's possible that this is where the receptors are in the sea turtle,
42:06only they're much more effectively used in them than in us.
42:10Essentially, the turtles have GPS-type precision.
42:14As they orient towards the magnetic field,
42:17the magnetic crystals could either repel or attract one another,
42:20creating tiny forces that could be picked up by proteins,
42:24which in turn send signals to the brain about where to go.
42:27They line up when they're kind of like in a positive area,
42:30and then they don't line up when they're in a negative area,
42:33showing that it's not the right area to be in.
42:35That is absolutely amazing.
42:38Part of what's so mind-blowing to us as humans is that although we know the magnetic field to exist,
42:43we never actually sense it.
42:45Although it sounds fantastical, scientists have already observed navigation
42:48by way of magnetite response in bacteria, salmon, and trout.
42:52But sea turtles are the superhero of this power,
42:55especially as they seem to be born with some magnetic maps already programmed.
42:59There's probably some type of genetic memory there as well as physical memory,
43:04and it's somehow combined.
43:06And as humans, we don't have a genetic memory that we're conscious of.
43:11It's all learned.
43:12But a lot of animals do have these genetic drives to do certain things
43:17and behave in certain ways.
43:19And the magnetic sense of the sea turtle is one of those that drives their lifespan
43:24in terms of their migrations.
43:26Part of the sea turtle's leading edge, of course, is its wise old age as a species.
43:31One of the amazing things about biology is it's been able to use so many of the different physical properties
43:39of our universe to its advantage.
43:42And one of them is using the Earth's magnetic field.
43:45Meanwhile, until we can find ways to tap into our cellular magnetite,
43:49we'll be stuck with our conventional, less perfect navigational tools.
43:53Historically, navigation via compass isn't particularly accurate.
43:58Compasses are somewhat determined by the local magnetic field, so generally points north.
44:05But if you want to go five degrees south of east, it's really hard to continuously judge that direction.
44:11I can't set a heading from England and hit a specific beach in Jamaica.
44:16I mean, this is some really serious underlying basic physics that goes into being able to tell you
44:24where on the surface of the Earth you are within a few meters.
44:27But somehow, this turtle's evolved with the same capability. It's astounding.
44:32And it is yet one more of the animal kingdom's extrasensory phenomena that pushes our human imagination.
44:38Whether the magnetoreception of the sea turtle or the red fox, or the flabbergasting bill sense of the platypus,
44:45nature has engineered additional senses sensitivities in many animals that are just outside of our comprehension.
44:51But despite being out of our grasp, as these traits provide inspiration for our own machines, devices, and technologies,
44:58they also continuously advance and improve our lives as human beings.
45:28and even if you think the word of the signal of the human being is a natural in nature,
45:30So thanks for watching.
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