Snakes: Scaly, Serpentine Sensations!

[Music] snacks danger noodles nope ropes snakes what is it about snakes that intrigues us so much is it their deadly venom their spongy mouths or their international travel i'm serious snakes appear in so many places it's more surprising when a region doesn't have them and sea snakes are a thing so you'd think they would have swum pretty much everywhere by now but if that's the case why haven't they made it to the atlantic ocean yet well here's hank with the answer sea snakes are the most common group of marine reptiles in the entire ocean with almost 70 individual species but despite their impressive diversity none of them live in the atlantic ocean which is weird and also nice there's a whole ocean with no snakes in it but also there's an entire ocean of snake food and living space out there so what's going on the answer lies in their evolution their biology and a weirdly dry part of the ocean first reason is deceptively simple modern sea snakes didn't evolve in the atlantic all sea snakes alive today evolved in a part of the pacific known as the coral triangle and nearby regions with most species evolving in the last two and a half million years so they might not have started in the atlantic but they've had millions of years to theoretically move there and establish new populations but they haven't in part because it's a pretty big ocean for such little reptiles only one species of sea snake the yellow-bellied sea snake lives in the open ocean most of the others only live in near shore shallows the yellow belly is the only species that would have had much chance of making it to the atlantic but each of the different ways it could even hypothetically reach the atlantic has its problems like going around the tip of south america or africa might be too cold yellow-bellied sea snakes need temperatures above 20 degrees celsius in order to be toasty enough to breed and too far below 18 and they'll flat out die given an annual mean ocean temperature of less than 17 degrees off the coast of south africa that's a no-go yellow-bellied sea snakes actually can live directly south of africa but it might be that the ocean is too cold just west of there so they still couldn't make the whole trip oddly enough going around africa might also be too dry sea snakes can't drink salt water instead they drink a thin layer of rain water that floats on the surface of the ocean after storms yes this is the thing that's wild but the southwest coast of africa includes the namib desert with its infamous skeleton coast this region may go years without rain even out at sea sea snakes going this way could become dehydrated and die and they might not have any luck trying to go the other way where north and south america are the obstacle millions of years ago there was an open corridor between the pacific and the atlantic in what is now panama a much warmer route than rounding the southern tips of africa or south america trouble is the ithness of panama formed long before sea snakes evolved blocking them from simply swimming from one ocean to the other we humans have opened that passage back up in the form of the panama canal and there have been reports of individual sea snakes on the caribbean coast of colombia which presumably made the trip through the canal even so scientists think it's unlikely they'll establish an actual breeding population via this root so in the end even though it might seem like the atlantic would be a nice home for the sea snakes with warm water and tasty prey their biology and evolutionary history put that possibility pretty much out of reach the fact that there's water on top of the ocean still kind of blows my mind like thinking about how sea snakes drink water is fascinating but apparently how regular old land snakes drink water is also fascinating they don't just slurp it up like we do they don't need to because their mouths are sponges so how does that work have you ever looked at a snake and wondered how does this thing drink well animal physiologists certainly have and the answer isn't obvious snakes don't have lips like we do and it's pretty clear that their skinny forked tongues weren't built for lapping up water and they also don't grab mouthfuls of water and tip their heads back to swallow back in the 1990s researchers thought they'd figured this conundrum out but it turns out they missed something and that something was that at least some snakes have sponge mouths that literally soak up water those scientists in the 90s carefully watched boa constrictors brown tree snakes and eastern rat snakes while they drank in between videos and some fluid dynamics modeling they determined that the animals were relying on suction essentially by rhythmically contracting certain muscles in their mouths and throat they could suck water up and push it back continuously without having to tilt their heads and this mechanism works because the snakes can seal their mouths shut to drink kind of like when you close your lips around a straw but then researchers observed snakes drinking without sealing their mouths which just didn't make any sense until they realized that their mouths were basically sponges you see the floor and the roof of a snake's mouth are covered in soft tissues with lots of folds and it turns out the animal can expand the space between those folds ever so slightly the molecules coating these tissues are really good at attracting water and that attraction called adhesion is stronger than the water's attraction to its own molecules or cohesion so as the snake opens its mouth to allow water in it expands these folds and by a process called capillary action water molecules can be drawn up and in against gravity it's essentially the same as what happens with a sponge if you put a squeezed one on a wet spot and then slowly release the water will travel up and in and once the animal's skin sponge is nice and wet further movement of the bones and muscles in the jaw and head will compress the mouth this squeezes the water out from the folds so it can be swallowed now this sponge-like drinking likely occurs alongside the more active suction drinking rather than instead of it and it seems to be totally unique to snakes even though some lizards have similar folds of mouth tissues that tells us that they probably didn't evolve these folds for drinking more likely they're what biologists call an exception a trait that evolved for one purpose but now serves another scientists think they exist because snakes swallow their prey whole to do that their jaws need to open incredibly wide and wrap around their meal hence expandable skin so these folds probably evolved for eating and they just happen to be pretty useful for drinking too and there's probably more to this story the truth is scientists are still not completely sure how snakes drink some species seem to use both these methods others favor one and some might switch things up as they get older and grow bigger so it turns out that snake drinking is still a bit of a puzzle but what we do know is cool and weird and just i mean sponge mouths that just doesn't even seem real so snakes have expanding mouths that they can use to drink water sometimes the most extravagant adaptations help animals accomplish the simplest goals now another awesome adaptation that snakes have developed is venom awesome at least until the snakes start biting humans so in the event that we do get a venomous snake bite what can we do about it bitten by a venomous snake well you probably shouldn't waste three precious minutes watching this video but if you're going to do it anyway i can tell you that there is hope some animals have a natural resistance to snake venom like the snake eating honey badger which can be bitten in the face by a cobra and still not care but for people historically you just had two choices you could either just hope you'd recover or you could just die a lot of the time you did both but all that changed with albert colmette french researcher dedicated public health advocate and co-creator of the tuberculosis vaccine colmette also developed the first snake anti-venom in the late 1890s the story goes that colmette was sent to saigon in what is now vietnam by his mentor louis pasteur one of the fathers of microbiology to help inoculate people against smallpox and rabies one day a major flood swept through his village flushing up a bunch of monocled cobras that started biting everyone but colmette was like uh uh snakes and being an expert in the business of vaccine making he whipped up an anti-venom called kalmet's serum his technique was so solid that it remains largely unchanged today anti-venom works by stimulating the production of antibodies the highly specialized warrior proteins released by your immune system to neutralize dangerous antigens like viruses bacteria or in this case venom antivenom can't destroy a venom's toxins or reverse its ill effects but the antibodies they create can smother them preventing further spread and rendering them harmless and here's how you make it step one get some venom to make antivenom you need venom and if you're wondering about the name yes you can also call it antivenin if you want to venon is actually the french word and since he was french that's what it was originally called but a while back the world health organization decided that in english at least anti-venom made a lot more sense anyway to make an antidote for venom you need a lot of it so once you got your bag of deadly snakes grab one open its mouth over a vial and gently squeeze its venom glands until they're empty you'll only get a little bit of time so multiple snakes must be milked as they call it many times to get enough venom fun for example in 1965 the national institutes of health told famed snake wrangler bill host to collect about half a liter of coral snake venom it took him 69 000 milkings over a three-year period to reach that goal step two freeze the venom once the snake is milked the venom is freeze-dried to concentrate and preserve it step three use some other animal to make antibodies find a horse sheep or goat and inject them with little doses of the venom again and again over several weeks this allows the animal to build antibodies and fight off the venom the antibodies peak after a couple of months at which point they can be harvested by which i mean that up to six liters of blood is typically drained from the animal's jugular don't worry the animal isn't bled to death it'll live on to enjoy the process all over again step four purify concentrate and deliver after the bloodletting is done you filter out the antibodies and then purify and concentrate them into dose vials if you need it like right now then good but if you're just gonna store it up for the next snake handling encounter then stash it in the freezer the fact that anti-venom must be kept cold poses a serious problem for developing countries with scarce electricity unfortunately those tend to be the same places that are inundated with killer snakes you've probably noticed by now that this whole process isn't easy making anti-venom is expensive and time-consuming which is one reason why it suffers global supply shortages all the time a single vial may cost over fifteen hundred dollars and a victim may require twenty to thirty vials to fully recover from a serious bite but there are other ways remember bill host and his half liter of snake spit he practiced a form of mithridism the process of making yourself immune to a toxin by gradually taking non-lethal amounts he milked a hundred snakes a day with his bare hands and made his own decidedly lower tech anti-venom leaving the horses out of it and using his own body he pretty much single-handedly saved 21 snake bite victims by flying around the world donating transfusions of his own blood he lived to be 100 years old surviving 172 snake bites and only losing one finger to which i say dang well that definitely takes longer than three minutes to make so hopefully this video is not the first result that comes up when someone searches for help i just got bitten by a venomous snake but on the other hand let's consider the hypothetical scenario where the snake doesn't bite you you bite it because as internet pedants just love to point out snakes are generally venomous not poisonous they inject venom with their bite but these neck snakes are poisonous so you probably just shouldn't eat snakes in general just in case if you've ever called snakes poisonous around a herpetologist or you know that friend of yours you know which one i mean there's a good chance you'll receive a lecture about the difference between venoms and poisons and it's true that most snakes aren't considered poisonous but nature loves an exception meet the tiger keelback they got the best of both worlds poison for their predators and venom for their prey it could be easy to confuse the terms venom and poison but the difference does actually matter both are made up of toxins biological chemicals that mess with body functions in small amounts the technical difference has to do with how they get into a victim's body poisons enter passively by being eaten breathed in or absorbed through the skin and because of that they're usually defensive an organism's way of saying hey don't touch me you will regret that venoms on the other hand are actively injected into the body like via a pair of pointy snake fangs for example venom can certainly be used defensively but often venomous animals are predators that use their toxins offensively so they can enjoy a meal without all that troublesome struggle since venoms and poisons tend to be used differently they usually contain different kinds of toxins so a doctor would want to treat a snake poisoning differently than a snake bite or what's known as envenoming and the distinction is particularly important if the snake in question is a tiger keelback these snakes can be found across southeastern asia and they belong to a huge and diverse family of snakes called the kalubridi these are sometimes referred to as rear fanged snakes because unlike rattlesnakes or cobras which pump venom forcefully through hollow fangs in the front of their mouths collubrid fangs sit further back in the jaw and deliver venom along open grooves and they have to kind of chew on their prey a bit to get the venom moving most of the time tiger keelbacks use their venom to take down tasty fish tadpoles and their favorite frogs and toads they rarely bite humans but when they do it's not a fantastic experience for the human the venom can cause hemorrhaging and mess with blood clotting leading to excessive internal and external bleeding and in several known cases death thankfully anti-venom is usually an effective treatment if delivered in time now all this talk of killer snake bites might sound scary but it's important to remember that snakes don't want to bite you really they don't they'd much rather save their venom for their prey they don't waste it on something they can't eat and that may be partly why the tiger keelback usually fends off threats another way on the back of these snakes necks are several pairs of nuchal glands if the right pressure is applied these glands crack open and spew out a stinky toxic yellowish pus the poisonous nature of this stuff was first noted in 1935 when a scientist who was dissecting a keel back cut into its nuchal glands accidentally spraying the poison right into his eye which is just one of the many stories that science teachers have heard and why they get so fussy about you wearing your safety goggles the poison contains bufadenolides which can cause acute pain and temporary damage to the cornea if they get in your eyes when ingested or inhaled they can irritate any tissue they touch and even cause heart problems and the snakes know how to use their poison when confronted with danger they assume an arched posture and aim their neck towards the threat sometimes they'll even swing their neck at an attacker poison glands first in a maneuver that scientists have delightfully named a neck butt maybe the most interesting thing about this poison is that they don't make it they pick it up from the toads they eat research has shown that tiger keelbacks living on toad-free islands don't have these poisons but they can become poisonous if given toxic toads and you'd think that a lack of poison would be a problem for a newborn snake but it turns out mama keelbacks can pass toxins along to their young it's unclear if she adds it to the yolks or just bathes her eggs in the stuff experiments have shown that keelback babies absorb toxins through their eggshells either way by the time the baby keelbacks hatch they are ready to defend themselves and here's something super weird the snakes are more likely to flee from threats than face them neck on if they've been deprived of toads suggesting the animals somehow know when they're poisonous also the snakes don't just take the toad toxins as is and stick them in their glands they actually modify them chemically to make them even more potent the tiger queueback is definitely the best known example of a poisonous snake but it's likely not the only one other related species have nuchal glands so they might have poisons of their own that simply haven't been studied researchers found that other snakes like garter snakes can eat so much poisonous prey their organs become toxic to predators since most people don't usually eat snakes there could be a number of species that would make us sick that we just don't know about so future studies may reveal that the tiger keelback isn't that much of an exception after all in the meantime you can tell that pedantic friend of yours that there definitely are poisonous snakes so so venom isn't the only way that snakes can kill us great so okay snake bites you you bite it i think we've covered all the options except for one what happens when the venomous snake bites itself rose we need the answer snake venoms are some of the world's deadliest substances so snakes have to be super careful with them i mean if you have giant muscles you don't want to punch yourself in the face and obviously if you have potent venom you don't want to accidentally bite yourself or so you'd think but actually in most cases if a snake bites itself it's pretty anti-climactic we've known this for a long time over the centuries a not so small number of perhaps ethically questionable scientists have found themselves overcome with morbid curiosity so they've injected snakes with their own venoms to see what would happen and the short answer is usually very little if anything at all most venomous snakes simply aren't a danger to themselves even though in other animals their venoms do some serious damage snake venoms are full of toxic peptides and proteins molecules that cells make that cause all sorts of horribly horribly unpleasant things like neurotoxic venoms mess with neurons and keep them from sending signals properly and that means at their worst they can cause life-threatening paralysis meanwhile hemotoxic venoms do terrible things to your circulatory system like preventing blood clotting and causing uncontrolled bleeding some snakes even wield cytotoxic venoms ones that kill cells and can cause parts of your body to simply die all of these toxins tend to do their nefarious work using elements of cells that are found across vertebrate lineages and even in invertebrates like bugs essentially you can think of the toxins as keys that unlock really standardized doorknobs found in all sorts of buildings that's why they're dangerous to us even though we're not the buildings they're trying to break into and why it's weird they're usually not dangerous to themselves even though they have the same kind of doorknobs okay the analogy might be getting a little strained but i think you get the picture we didn't figure out how the snakes were surviving their toxic cocktails until somewhat recently and it turns out they can each have several strategies for starters even though venom toxins tend to attack really important pieces of our biology some snakes are able to tweak their versions of these targets it's the molecular equivalent of changing the locks for example since neurotoxins are positively charged they're attracted to negatively charged parts of receptor proteins on nerves but certain species of snake have just you know reverse the polarity of their receptors see that trick isn't only useful on the starship enterprise instead of negatively charged receptors they have positively charged ones that literally repel the positively charged toxins and this isn't just seen in venomous snakes that need to protect themselves some non-venomous snakes have similar tweaks to their receptors presumably to help stay off their cousin's menu other snakes like the egyptian cobra are able to tack sugars onto their nerve receptors which physically block the toxins from reaching their target but it's not always possible to modify the stuff toxins attack changes can mess things up and remember these are super important parts of our bodies so trying to toxin proof them could be life-threatening all on its own so some snakes have built-in anti-venoms biologists have suspected venomous snakes essentially leak toxins into their bodies constantly this lets their immune systems develop targeted defenses much in the same way a vaccine prevents you from coming down with a disease but some take this idea one step further they've evolved anti-toxins that they keep in their bodies all the time that way if some of their venom gets where it doesn't belong the most dangerous bits are shut down before they can cause real harm for instance some snakes produce proteins that bind and inhibit their venom's phospholipases enzymes responsible for a lot of nasty effects of hemotoxic and cytotoxic venoms these versatile enzymes can do a range of awful things like prevent blood clotting and kill cells so it's no wonder that snakes like the short-tailed pit viper have several different phospholipase inhibitors in their blood what's extra cool about natural inhibitors is that they could help us develop better anti-venoms modern anti-venoms save a lot of lives but they're not perfect they're expensive only cover a limited number of snakes and generally require cold storage which means it can be hard to get them to the people who most need them so doctors would love to find a good alternative and the snake's own natural inhibitors hold a lot of promise and before we wrap this up it's worth noting that not all snakes have these built-in protections some can and have killed themselves with a misplaced bite like in 2016 australian researchers witnessed the unfortunate death of a brown tree snake that bit itself which suggests that brown tree snakes aren't immune to their own venom and even ones that are may not survive the bite from other members of their own species since there can be a lot of toxin variation between individuals like in 1932 scientists made a couple of black-tailed rattlesnakes bite each other and let's just say that things did not end well for either rattlesnake and in many cases though the animals built-in venom defenses can prevent personal tragedy so while i imagine it's super embarrassing for a snake to accidentally bite itself most can slither away mumbling i meant to do that an immunity to your own venom suddenly sounds like a really good adaptation and it makes me wonder if humans could develop an immunity to a snake's venom too if i were to ask you whether it's safe to drink snake venom you'd probably have a very firm answer right away either you'd automatically say no because snakes wield deadly poisons or if you're a science pedant you might unequivocally say yes because snakes wield venoms not poisons well i'm here to tell you that actually both of those answers are wrong and at best the correct answer is maybe let's start with the surefire no the science patents out there are right when they point out that venoms and poisons differ namely by the route of administration both fall under the broader umbrella of toxins meaning they cause problems in relatively small amounts but venoms get into you via wounds like a snakebite while poisons are either inhaled swallowed or absorbed through the skin and yes this difference matters when it comes to how toxins affect you since venoms go directly into your bloodstream it doesn't need to be able to survive a trip through your stomach so venoms often contain big somewhat delicate molecules that can be inactivated or destroyed by your digestive juices but before you run out to do a shot of snake venom let's move on to the misconception behind that solid yes answer you see there may be no evolutionary reason for venom toxins to work when consumed but that doesn't mean that they never do what you really need to know is the venom's oral toxicity how different amounts affect you when ingested and oral toxicities tend to be lower than injected ones that's in part because of those digestive juices we mentioned also there's the physical barrier of your gut lining so odds are some of the stuff just passes through you without getting absorbed that doesn't mean venoms are guaranteedly drinkable for instance the venom of the blue ringed octopus contains the potent paralytic tetrodotoxin which is roughly 40 times less toxic when swallowed than when injected but still it's a super deadly poison so if you did somehow manage to obtain a shot glass full of venom from these golf ball sized octopuses you definitely wouldn't want to drink it i can't actually say that it would kill you because we haven't tested this venom's oral toxicity but that's kind of the thing we haven't tested most venoms that way there simply hasn't really been a reason to so we don't know if they're safe to drink though we do have some evidence to suggest that they aren't for instance in a study published in 2015 rats that ingested cobra venom ended up with damage to their livers reminiscent of what happens after a regular bite plus there's been at least one case where someone almost died after drinking snake wine a beverage prepared by steeping an entire venomous snake in alcohol and this guy wasn't suffering from run-of-the-mill alcohol poisoning he was admitted to the hospital because his blood had stopped clotting properly a symptom often caused by snake venoms and he got better after receiving antivenom researchers in australia are actually hoping some venom toxins work orally on insects that is that way they can more easily be used as pesticides and so far 70 of the spider venoms they've tested killed the fruit flies that ate them which sounds promising as far as pesticides go now that doesn't mean they're dangerous for us to drink but still the research is further evidence that venom toxins can do their nefarious work when ingested so can you drink snake venom i mean maybe it could depend on the species of snake but we haven't done the tests to find out and making assumptions based on the difference between venoms and poison is a terrible idea so moral of the story just don't drink venom snakes are an important part of our ecosystems and they're pretty cool so we're better off not roping them into our dumb stunts and we have anti-venom technology so humanity probably won't fall to the snake revolution anyway thank you for watching this episode of scishow and if you are interested in the eventual overthrow of humanity you could check out this list of nine animals that will outlive us [Music] you

Channel: SciShow

Views: 229,909

Rating: 4.919467 out of 5

Keywords: SciShow, science, Hank, Green, education, learn, snakes, venom, sneks, danger noodles, nope ropes, Why Are There No Sea Snakes in the Atlantic?, Snakes Use Their Spongy Mouths to Drink, How to Make Antivenom, Behold—Poisonous Snakes! (Yes, You Read That Right), What Happens When a Venomous Snake Bites Itself?, Is It Safe To Drink Snake Venom?, Snakes: Scaly, Serpentine Sensations!

Id: sVC7bpi54fQ

Length: 26min 53sec (1613 seconds)

Published: Sun Aug 15 2021

Reddit Comments

[u/ChemBDA]

SNAKES!