The Most Hardcore Creatures on Earth | Compilation

[Music] we humans like to think that we're pretty tough but lots of other animals put us to shame and sometimes the grittiest creatures on earth aren't what you'd think take desert kangaroo rats for example while you might laugh in the face of danger they kick it literally i'll let olivia explain you may not think much of the desert kangaroo rat this small animal with its large back legs might seem like a run-of-the-mill rodent at first but don't let its modest appearance fool you kangaroo rats are mighty beasts that don't think twice about kicking deadly rattlesnakes in the face the kangaroo rat lives a simple life by day it builds burrows in the sand and by night it forages for seeds to store in those burrows and when it does it has to avoid predators lots of predators the rat's flesh is sought by coyotes foxes hawks owls and snakes including the sidewinder rattlesnake you know the one that does that crazy dance across the sand yeah that guy and they're especially hard to avoid that's because they're ambush predators that lay in weight at the best seed spots they have thermal vision sharp fangs a potent venom and can deliver a strike in a tenth of a second luckily desert kangaroo rats have evolved special countermeasures this kind of arms race when two closely interacting species influence how the other evolves is called co-evolution take the snake's thermal vision for example to get around that a kangaroo rat can drop its surface body temperature especially around the feet and ears and make itself less noticeable it may also drum one or both of its feet letting the snake know that its ambush is ruined and if that's not enough to deter the snake the desert kangaroo rat still has tricks up its sleeve or well pants its most valuable assets are its huge back legs which can propel the 10 centimeter rat up to 3 meters away kangaroo rats have disproportionately large muscles tendons and bones which they need to generate and withstand the forces of their jumps because unlike their larger namesakes their big tendons and muscles don't act like springs jumps are made with pure muscle power that means more stress to the leg bones and muscles but the rat doesn't have to get into a particular position to leap and that allows it to react quickly an alert kangaroo rat can react in as little as eight milliseconds and leap its whole body away in about fifty roughly one half the time it takes for the snake to lash out and it doesn't even need to see the snake coming kangaroo rats have specially modified inner ears which allow them to hear when a strike happens in complete darkness they can also use those legs to kick sand at the snake's face or just kick the snake outright a powerful blow can stun the would-be predator allowing the rat to make its escape and whether kicking or jumping the rats have a huge advantage when scientists have watched these battles play out in the wild only 1 in 23 strikes results in a win for the snake of course the sidewinders haven't completely lost this evolutionary arms race scientists think that they can detect the rat's change in temperature for example if they realize the element of surprise is gone they can save their energy for a more unsuspecting meal but at least for now the kangaroo rats seem to have a jump on things well standing up to a venomous animal is pretty hardcore but grasshopper mice take the idea one step further not only are they totally unafraid of scorpions they use their venom as a painkiller here's olivia again with the details the deserts of the southwestern us are home to an ordinary looking mouse with a superpower it's immune to scorpion venom in fact grasshopper mice aren't just immune to the nasty stings of the bark scorpions they eat the rodents have turned the scorpion's best weapon into a potent drug that temporarily dulls their pain allowing them to eat the toxic critters with impunity bark scorpions are a group of dangerous arachnids some species are even toxic enough that they'll occasionally kill people but when they sting mammals like us it's usually in defense so they've evolved a venom that's notoriously agonizing a feat accomplished by hijacking nerves it contains toxins that mess with a protein called nav 1.7 that's a sodium ion channel a tunnel through the membrane which allows sodium molecules to move across which is used by our pain-sensing nerve cells it has a gate of sorts which when open lets a flood of sodium ions through to generate an electrical pulse and that pulse is essentially the start of the ouch signal that's sent to our brains normally nav 1.7 senses small changes in ion concentrations that happen in response to injury but bark scorpion venom has components which force its gait open in the absence of these triggering pain really really bad pain most mammals also have nav 1.7 channels in their pain sensing neurons so scorpion venom hurts like heck in humans most rodents and lots of other furry critters a pretty effective way to say stay back but grasshopper mice which eat these toxic scorpions have found a unique way to get around this you might think they've changed their nav 1.7 proteins to be resistant to the venom like scorpion eating bats have but nope instead they have an altered version of a different sodium channel protein nav 1.8 it's found in the same nerves as nav 1.7 and one of its jobs is to help transmit pain signals to the brain basically it's one of the runners in a neuronal relay and can take the baton from nav 1.7 in other mammals nav 1.8 doesn't react to scorpion venom but in these mice it does the venom toxins bind to it and shut it down dulling the mice's pain so the venom still turns on the pain pathway by opening nav 1.7 that signal is just immediately stopped from going anywhere if that sounds incredible well the researchers that discovered it were pretty surprised too but they confirmed the painkilling effects in the lab injecting the mice with scorpion venom allowed them to shrug off injections of pain-causing substances like formaldehyde which otherwise make the mice quite unhappy and when they looked at these mice's genes they found the difference comes from switching just two amino acids out of the hundreds that make up the nav 1.8 protein that's all it took to transform the scorpion's agony inducing venom into a painkiller instead so don't let mice's meek reputation fool you turns out some of them are way more hardcore than you think well i'm starting to think we don't give rodents enough credit now for our next secretly hardcore creature trinidadian guppies they're cute and tiny but don't let those looks fool you they don't cower when danger looms they dare bigger fish to attack here's michael to explain why convincing a predator to attack might seem counterproductive if you don't want to be eaten and getting them to attack your head might seem like the absolute worst idea ever but that's exactly what these little guppies do they taunt larger fish and get them to attack at their eyes and that's actually safer for them let me explain trinidadian guppies are eaten by bigger fish called cichlids which are ambush predators so when a cichlid is hungry it hides and waits for a smaller fish to swim within reach and then boom it's like a yummy fish dinner was delivered straight to its door but these guppies have figured out how to make the cichlids attack on their terms allowing them to lure the predators into missing first they draw the cichlids attention using conspicuous coloration highly noticeable colors that get the hunter looking where the guppy wants it to attack but here's the thing if the guppies were always conspicuously colored they'd know where a cichlid would attack but not when which is why they can change their color and specifically they can change the color of their eyes normally their irises are silver but they can turn them black see the color comes from cells that have sacks of pigment inside melanin the black pigment that guppies use to change their eye color is found in a special type of cell known as a melanophor and when melanin is at the center of the melanophore light can pass through most of the cell but if it's spread out it creates a layer that absorbs light and makes the cell look black so when a guppy spots a predator hormonal and nervous responses signal their melanophores to rearrange proteins pull melanin from the center of each cell out across the entire thing and the whole eye goes black in about three seconds those black eyes are much more noticeable so when a guppy changes its eye color it's basically daring the cichlid to aim for its head which i know seems like the last place you'd want to be bitten but if the attack is aimed there instead of its middle where the cichlid would usually attack the guppy can bend around its center to dodge the predator so basically they use their eyes kind of like a matador cape luring danger into lunging at the wrong angle and allowing the guppy to twist away at the last second and escape and the international team of researchers who wrote about this amazing tactic in a 2020 current biology paper found that larger guppies are even better at this as their center pivot point is even further from their eyes so they think this adaptation may have allowed this species to evolve a bigger size overall so next time you're faced with a stressful situation consider tackling it like a guppy head on now those fishies aren't the only fearless little animals out there fuzzy velvet ants look like they'd be fun to cuddle i mean as much as any ant could but most creatures are smart enough not to mess with them and for several good reasons i'll pass it back to michael for the lowdown no one wants to be eaten that's why the animal world is full of adaptations to stop predators like hard shells bright markings and painful stings still most creatures regularly end up on someone's menu except for velvet ants these little insects combine a ton of defenses into one very unappetizing package and they're so terrifying that pretty much nothing eats them velvet ants aren't technically ants they're wasps the males can fly but the females don't have wings what they do have is a massive stinger in fact relative to their size they've got the longest stinger of any wasp and some seriously painful venom too still they don't rely on it alone to deter predators they also have a super tough exoskeleton it takes about five times the force to crush a velvet ant as it does to squish a bald-faced hornet for example plus they're round and slippery making them hard to bite down on something researchers realized firsthand while trying to crush these things the crutters kept slipping out of their grasp of course the velvet ant doesn't want it to come to that so they employ an array of warning signals their velvet sections are brightly colored as a bold visual aposomatic signal they also literally sound the alarm by rubbing a section of their abdomen to make a loud squeaking noise and they can release smelly alarm pheromones these by themselves can deter some predators and the combinations of defenses and warnings is super effective it seems to train other animals not to mess with them too like in one experiment lizards that had a run-in with a velvet ant still avoided them over a year later and in another birds were wary of eating one of their favorite tasty treats simply because researchers had painted them to look like velvet ants predators don't even need to have encountered a specific species of them many velvet ants mimic each other's coloring in what scientists call mullerian mimicry so if a predator encounters one they're unlikely to mess with any of the others in fact scientists have set up showdowns between velvet ants and many potential predators just to see what bites they tried spiders lizards actual ants birds moles gerbils shrews almost all of them avoided the velvet ants entirely and the few that did catch them mostly spat them up as far as anyone can tell toads are the only animals that occasionally eat velvet ants they don't have an easy time of it they swallow their food whole and velvet ants can survive for over 20 minutes inside a toad's stomach so even toads end up spitting them out more often than not velvet ants extreme investment in defense likely has something to do with their lifestyle females can't fly away from predators plus they spend lots of time on the ground looking for places to lay their eggs see these ants are parasites to reproduce they find nests of other bees and wasps and lay their eggs inside when the larvae hatch they feed on the other species helpless young oh also those nests are often well defended by other stinging insects so i guess if you're regularly that rude to your neighbors you'd better be as tough as a velvet ant so to sum up velvet ants small but mighty but next let's shine a light on an even smaller hardcore creature rotifers and it can be a pretty bright light because these microscopic critters can withstand way more radiation than you or i can which apparently has something to do with their aquatic lifestyle hank lay it all out for us deloid rotifers are microscopic animals that look like cigars with a brush on the end they are not very impressive looking but they are some of the toughest creatures in the animal world their superpower if their dna is shredded to pieces whether because of a lack of water or a blast of radiation they can put it back together they might even use the situation to their advantage and acquire new genes in the process it's all in the name of survival in aquatic habitats that can dry out and leave the rotifers without a place to live you might be thinking wait this sounds familiar because tardigrades famously survive under similar conditions we talked about them way back in scishow's fifth video ever but stay with me because rotifers are arguably even more hardcore and they do it in their own way there are over 400 species of deloid and many of them can tolerate desiccation or drying out they live in droplets on mosses or in temporary ponds which can dry out and force the rutifers to enter a sort of suspended animation known as anhydrobiosis their bodies contract into a dried out form that's less than 10 percent water which is too dry for biochemical reactions to happen it's hitting a complete pause button on being alive there are serious challenges to surviving this dried out state one of them is the fact that it's extremely bad for dna at this level of desiccation dna molecules just snap both strands of the backbone holding them together give way in what's termed a double strand break and dna doesn't work if there's a break in the middle of a sequence the cell needs to use even worse most organisms aren't very efficient at repairing double strand breaks the usual repair processes might stick the wrong ends together or introduce new base pairs either of which would cause potentially dangerous mutations celluloids are known for their resistance to radiation which also causes double strand breaks a 2008 study by researchers in massachusetts found that deloids could withstand a dose of radiation that caused about 500 breaks per copy of their genome and only suffer a drop in their ability to reproduce of about 20 percent but their resistance to radiation is probably a coincidence an unintended but super awesome side effect of the fact that both radiation and drying out cause the same dna snapping problem the weirdest thing of all is that delwoods don't seem to fix their dna until they rehydrate it's not clear how they do this but it seems like maybe the proteins that fix their dna pull through the desiccation process even when the dna is damaged that was what researchers found in a 2012 study in the journal pnas deloids experienced dna damage from radiation at about the same level as other similar animals like nematodes but the damage to their proteins was kept relatively in check so maybe when the rotifers are exposed to water again the proteins fixed the dna and the rotor first swim away but stitching up their shredded dna isn't the only weird thing rotifers can do they can also borrow genes from other organisms including bacteria plants and fungi acquiring genes in the absence of sexual reproduction which by the way deloids don't seem to go for is called horizontal gene transfer bacteria do it all the time but it's incredibly uncommon in animals and yet as many as eight to nine percent of deloitte genes may come from other organisms at least one study has found that desiccating species of deloids acquire more foreign dna than their cousins who don't dry out which leads to the hypothesis that they actually do it while stitching their dna back together got some free dna ends here got a spare gene stick it in there maybe it'll even work we don't know for sure if this is actually what's going on especially because even deloids that don't dry out still have some foreign genes but this chaotic borrowing leads to perhaps the strangest example of how rotifers are so good at not dying a 2015 study in the journal plos one showed how horizontal gene transfer could help deloids survive desiccation as well as shed new light on an old mystery many desiccation resistant organisms including tardigrades fill their bodies with something to take the place of water when they dry out for a lot of these organisms that something is a sugar called trihalos trajalos hasn't been found in deloids but when the researchers took a closer look at one species genome they found that it had some genes for both making and breaking down trejollos one seems to have been acquired from plants and one from bacteria both appeared to be expressed in the deloid's genome so it was using the genes to make something although we don't know whether the products were biochemically active the breakdown gene was expressed more than the building one leading the researchers to speculate that trehalose could be produced in deloids than broken down too quickly to be detected whether this is an actual mechanism for deloids to survive desiccation is far from clear still it's pretty incredible for an organism to potentially piece together an entire biochemical pathway from bits it finds laying around which is what makes rotifers some of the most incredible survivors of the animal world like some bizarre zombie macgyver they're able to piece themselves together all the way back from the practically dead we've still got a lot to learn about how they do it but they sure are talented at protecting themselves and last but certainly not least we have one more microscopic animal to talk about i mean you didn't really think we'd get through a whole episode about hearty critters without mentioning tardigrades did you of course not hank take it away do me a favor right now and picture in your mind the toughest animal on earth whatever you think it is and now imagine what that animal would do in the most inhospitable environment that you can imagine so for example if you thought of a grizzly bear on top of mount everest being attacked by a swarm of silverback gorillas you would be wrong that is neither the toughest animal nor is it the most inhospitable environment but i thank you for the visual image that was a good one so you want to know what the toughest animal on earth is well voila there you have it my friends it is the tardigrade also called a water bear or a moss piglet because they're plump and waddly and they like to suck on moss and you may have noticed they're actually kinda cute they're what scientists call extremophiles which means they don't give a crap about where they live the tardigrade's secret is that when the environment gets too tough they just shrivel up and die for a while with the option of reviving when conditions improve and that is the weird thing about tardigrades they're so extravagantly tough like for no real reason they're just supposed to like waddle around on moss and suck up water that's their job and yet in their dormant state they can withstand temperatures close to absolute zero and up to 300 degrees fahrenheit they can survive being exposed to 1 000 times the radiation that would kill an elephant they can withstand pressures up to six times what you find in the deepest oceans on earth what what is the point of that there's no place that that would be useful on earth and you had better believe that we've been sending these little waddlers into outer space because what is the most inhospitable environment yes it is space in fact scientists think that tardigrades may be the key to understanding how life began on earth back in 2007 nasa put a bunch of tardigrades on the space shuttle then they opened up an airlock door and left them outside in the vacuum of space for 10 days being exposed to crazy amounts of uv radiation then they brought them back to earth and when they got there the tardigrades were like what's up they were happy and healthy and some of them laid tardigrade eggs and had a little tardigrade babies that were completely normal and we keep doing it earlier this year on the very last mission of the space shuttle endeavor we sent some tardigrades up in the european space agency sent some tardigrades into space as part of a mission called tardigrades in space which isn't clever until you realize that they shortened it to tardis so the question is why do we keep shoving these adorable little beasts uh into the vacuum of space it doesn't seem like a very nice thing to do well one because we want to understand how tardigrades work just scientifically how they can possibly survive these intense horrible inhospitable environments and two because we're interested in proving the panspermia hypothesis that is right panspermia a word i'm not going to make a joke about so imagine for a moment the meteorite slamming into our planet and this meteorite is so large that it actually ejects pieces of the earth into outer space now imagine on those pieces of earth that got ejected into outer space there are tardigrades if that little organism could survive the vacuum of space long enough to then fall down onto another planet it could seed that planet with life if life can be transmitted in that way then it becomes much more likely that life is a very very common thing in our universe panspermia hypothesis has been around for a long time but thanks to tardigrades it's starting to look a lot more credible so we can already thank these little beasts for being a great proof of concept for us but of course they will never know that we are so in their debt they're just going to keep walking around on moss sucking water off and occasionally visiting other planets ah those cute little moss piglets what a wonderful one to end on thank you for watching this scishow compilation if you enjoyed learning about these amazing abilities i bet you'd love our monthly after hours podcast in it hank and our content editor christy explore the wildest features of life on earth stuff that we really can't talk about here because it's not so family friendly we make the podcast as a thank you to our amazing patron community because we couldn't do any of this without them so if you're one of those awesome people thank you and if you're not a patron you can learn how to support the team here at scishow and even listen to a sample episode of after hours by heading over to patreon.com scishow [Music]

Channel: SciShow

Views: 178,136

Rating: 4.8924074 out of 5

Keywords: SciShow, science, Hank, Green, education, learn, desert kangaroo rats, grasshopper mice, Trinidadian guppies, velvet ants, rotifers, tardigrades, Stefan Chin, The Most Hardcore Creatures on Earth

Id: Gar-FGvvFu8

Length: 23min 3sec (1383 seconds)

Published: Wed Feb 24 2021