The Insane Biology of The Poison Dart Frog

this video is brought to you by brilliant the best way to learn math data science and computer science interactively deep in the forests of Central and South America some of the world's deadliest organisms lurk these creatures contain such toxic chemicals that only tiny dose is needed for them to kill full grown human poison dart frogs might be bright cute minuscule amphibians but they are absolutely Nature's version of around and find out just 2/10 of microgram of poison could kill human making this organism 100 times more lethal than the deadly inland taipan snake and there's absolutely no antidote to their poison no treatment to save you from painful death and they're not exactly trying to sneak up on anyone through the use of camouflage in fact they're downright flamboyant their colors serving as warning to wouldbe predators the deadliest of the family of poison dart frogs is known as the golden poison dart frog and has enough poison on its skin to kill more than 20,000 mice this little dude who only grows up to 47 in size smaller than your thumb is absolutely covered in betco toxins this alkaloid poison causes complete muscle paralysis shutting down the heart the diaphragm and everything else within minutes their deadly secreet ations have been used by indigenous people for poisoned blow darts since pre-colombian times which is what initially gave the frogs their name these poison darts are enough to drop monkeys and birds in their tracks nerve paralysis is almost instantaneous today there are several hundred species of poison dart frogs spread across tropical forests in Central and South America besides the golden poison dart frog some of the other notable species are the strawberry poison dart frog who name is too tasty for its own good and who has varietal that is considered to be wearing blue jeans there's the green and black poison dart frog which looks like chocolate mint situation and the dying poison dart frog which gives sort of Sour Warhead Vibe other of the more deadly species are the splashback poison frog the granular poison frog and the fantasmal poison frog and all of these frogs are the most forbidden snacks of all because among the hundreds of species are hundreds more types of alkaloids many of which are deadly some of which were unknown to science before researchers started studying these frogs and yet poison dart frogs don't make these toxins themselves they collect them from their prey arthropods like ants mites and millipedes but how is it that they can eat things that are full of such brutal poisons and how do these frogs avoid poisoning themselves and how is it that Predators know to avoid these tiny colorful frogs of death poison dart frogs are the only vertebrate we know of in which coloration toxicity and diet specialization all work together the combination of bright colors and poison is known as aposematism essentially the frogs evolved to be as bright as neon signs at the same time as they evolved to Harbor toxic chemicals their coloration is warning eat me and you're in for bad time interestingly when the frogs are raised in captivity and fed diet of fruit flies they don't develop any of the toxins and if wild frogs are brought into the lab and fed non-toxic diet they gradually lose their poison most toxic species of animal like snakes or jellyfish have the ability to produce the dangerous substances on their own trait known as endogenous biosynthesis the ability to eat something toxic and harvest those substances for one's own protection is called sequestration and is pretty uncommon in the natural world that's what poison dart frogs do and they manage it in ways we don't completely understand these frogs have two types of glands on their skin mucus glands and sarus glands it's the second of these two glands that contain the toxic alkaloids alkaloids themselves are organic compounds that that contain nitrogen and they're not always toxic things like caffeine nicotine and quinine are all alkaloids and we've found plenty of uses for them but the alkaloids on the skin of poison dart frogs range from making them taste bitter to mild poison to absolutely lethal poison however only 10% of the known alkaloids on their skin have had their sources identified in the cases where researchers have found source for the toxin it's been through the Frog's diet one study found that strawberry poison dart frogs were getting lot of their poison via or rited mites these tiny mites are related to spiders and scorpions but are only about 1 in size and to defend themselves from being eaten they have their own toxic alkaloids unfortunately for the mites those toxins are just what the strawberry poison dart frog is looking for the frogs collect the alkaloids from the mites and move those same poisons to to their skin and the more they eat the more poison they collect other alkaloids have been traced to certain other arthropods tricyclics from certain beetles Spyro padin from siphoned millipeds and the most deadly of all betra toxins from melid beetles and in some cases the accumulation of toxicity for the frogs isn't linearly additive where eating one more Beetle equals one more dose of poison sometimes the frogs supercharg the poison they are collecting by modifying the structure of the alkaloids to make them more potent when some species of frogs eat arthropods that have specific alkaloid called pumiliotoxin they're able to selectively hydroxate it by adding an group and in doing so form new alkaloid called alop pumiliotoxin which is five times more toxic than the original alkaloid but the exact mechanism for how they move these toxins around their body is still bit of mystery what we do know is that they have poison glands near the surface of their skin and ducts that open up and carry the alkaloids to the surface of the skin when frog is attacked by predator and if the Predator ingests the poison death comes swiftly many of the dangerous alkaloids in the frog's skin are neurotoxins That Kill by permanently blocking nerve signal transmission to the muscles normally nerves work by generating electrical signals that transmit information this electrical signal is created by the flow of ions across their plasma membranes at rest the inside of neuron has negative charge which is created in part by positive sodium ions being pumped out of the cell then when stimulus occurs the sodium channels briefly open because there are many more positive sodium ions on the outside and the inside of the neuron is negative relative to the outside sodium ions rush into the neuron the the cell rapidly depolarizes and fires in action potential meaning the neuron fires its neurotransmitters but certain toxins can completely disrupt this process bet trato toxin for example binds to and irreversibly opens the sodium channels of nerve cells this means sodium ions can freely diffuse between the inside and the outside of the cell and thus the membrane potential of the cell is removed at this point point the cell becomes electrically dead the nerve can no longer transmit any signals which means every single muscle becomes paralyzed including the heart and the diaphragm once these stop working the organism is very dead other toxins from poison dart frogs Target things like the acetylcholine receptors which renders similar effect and what is consistently surprising about these Mighty little murderers is how they aren't poisoned by their own poison in one case scientists found certain frogs protect themselves by changing the configuration of The receptors on their neurons by single amino acid substitution this makes it so the toxin doesn't bind to their receptors allowing them to continue to function normally researchers have also found that the golden poison dart frog has Gene substitutions and mutations that make it immune to the effects of betra toxins and dozens of its other dangerous alkaloids but what we still don't know is how they manag to develop defenses against so many types of alkaloids puffer fish for example only have to deal with tetrodotoxin meanwhile poison dart frogs have immunity to dozens or even hundreds of dangerous alkaloids toxins that they don't even produce themselves and these poisons are so deadly that the golden dart frog is considered to be the most poisonous creature on earth even just touching the golden dart frog could be lethal espe especially if you have cut on your hand the poison could even be strong enough to enter through your sweat pores though don't think many people are willing to test that out to know for sure but considering that this poison is so toxic that it kills any wouldbe predator the first time encountering it how do Predators learn to avoid this brightly colored death frog given the fact that hundreds of species of poison dart frogs evolved to use bright coloration in combination with poisonous skin would seem to indicate that it's successful strategy and in one study scientists looking at color variations among poison dart frogs found that birds were more likely to attack blue frogs than more vividly colored yellow frogs suggesting that the birds were bit more worried about the brighter yellow prey the more conspicuous the Frog the safer it was but if the poison is so toxic from golden poison dart frogs that it's lethal if ingested 100% of the time How can any animal learn to avoid it one possibility is that every frog has different level of poison juvenile frogs for example have had less time to accumulate poison and may not kill the predator and instead give them highly unpleasant experience additionally predator does not need to ingest the Frog to be harmed by its toxins predator with wet nose who bumps the Frog while sniffing it will likely have bad time but perhaps not die these situations could allow the Predator to learn from past experience that bright frog is Bad Frog and Beyond this for some predators avoiding brightly colored animals May Simply Be hardwired genetically over millions of years predators that were more inclined to avoid brightly colored prey survived more often but what about Predators who don't even have color vision like the bullet ant and broat spiders both of these arthropods are big enough to prey on small frogs and are known to do so on fairly regular basis they also don't rely on color vision when they're hunting do they know to avoid the dangerous frogs researchers presented bullet ants and bromad spiders with two species of frog the non-toxic bransfords litter frog and the toxic strawberry dart frog bullet ants would eat juveniles of the strawberry dart frog but not the adults and the spiders wouldn't touch any of the toxic frogs no matter their age even though they did eat the non-toxic species these Predators still knew which frogs to avoid likely using meano and chemo reception but the poisonous frogs can't always be so certain that they're safe from predation one species of snake called the fire-bellied snake has evolved resistance to betco toxins in the golden poison dart frog it's the only known predator of this frog and the Royal ground snake another species in the same snake genus was observed to attack and kill three striped poison frogs it was the first time this Behavior has ever been seen in the wild so researchers will need to do lot more investigation but it does suggest something of an arms race between predators and the poison dart frogs but as dangerous as these frogs might be to Predators they are not Invincible even with their chemical Arsenal about quarter of poison dart frog species are classified as endangered or critically endangered and that comes down to habitat loss fungal infection and the exotic pet trade all factors that these small frogs can't fight against with their toxic skin but nonetheless these small frogs punch above their weight class in terms of lethality and show us that even the tiniest cutest things can be force to be reckoned with unfortunately for us humans we can't absorb absorb the poison that we eat and use it as weapon but there is something else that we can absorb and that is knowledge by understanding the genetic underpinings of the poison dart Frog's resistance to poison we one day might be able to learn how to be resistant to certain poisons ourselves by understanding the evolution of poison dart frogs their predators and their prey we will better understand how to conserve them understanding biology and the math chemistry and physics it all entails is the best tool we have to protect ourselves and protect the incredible world we live in and surprisingly there is free and easy way to practice these skills brilliant has so many courses on subjects that help you wrap your head around the math and science Concepts that are so important in understanding our natural world brilliant is the best way to learn math data science and computer science interactively I've always struggled with lectures and textbooks 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