Australia's Most Destructive Creature

in the 1930s australian farmers had a really big problem their sugarcane crops were being decimated by a voracious grub the larvae of the cane beetle which destroys the plant's roots after failed attempts at chemically controlling the grubs officials sought a biological solution they thought if they introduced a predator of the beetle the grub problem would go away at the time the thought process wasn't entirely unreasonable but it would turn out to be the single worst decision they could have made after hearing about a measure to control a similar cane beetle in hawaii with the voracious cane toad australian officials jumped at the idea after dutifully carrying out exactly zero studies of the potential impact on the australian environment they transported a hundred toads from hawaii and let them loose and with that single action the australian ecosystem was never the same one hundred toads quickly became one thousand and then ten thousand and then ten million and then a hundred million they have rapidly spread over much of the continent today cane toads properly known as bufo marinus or buffo toads are the most notorious of all invasive species in australia this lumpy guy is massive poisonous and seemingly unstoppable the biggest cane toad ever recorded was almost 40 centimeters or 15 inches long and weighed 6 pounds or 2.75 kilograms it eats anything it can fit into its mouth insects trash dog food small reptiles small rodents and even birds the one thing it doesn't eat though is the cane beetle cane beetles perch too high off the ground for cane toads to reach and the toads certainly can't get to the grubs underground so you could say there are some regrets cane toads are now moving westward at a remarkably fast pace and the australian government admits that it's unlikely that they will ever be fully contained since their introduction 87 years ago cane toads have been linked to the decline of several native species in the northern territory in queensland including the australian monitor lizard the northern blue tongued lizard the australian water dragon the king brown snake the common death adder and the northern coal many species are at risk of total extinction all because of this stupid ugly toad what is it about the cane toad's particular biology that makes it so destructive and able to spread so easily why are some introduced species worse than others and what can be done to stop them invasive species unfortunately have become a major part of our modern world they can be introduced to an area by ship ballast water accidental release or like in the case of the cane toad by misguided intentional human action but a common misconception is that any species found living in its non-native habitat is an invasive species this however is not the case many species are introduced to new areas without it being a problem most crops for example are non-native potatoes for example are from south america but are now grown on most continents without causing an issue honeybees were introduced to the americas from europe in the 1600s and have yet to cause any major problem a species only gets the invasive title when it causes harm to the environment displaces or out-competes native species hurts the economy of the area or becomes a danger to human animal or plant health the brown tree snake has eaten a dozen kinds of forest birds in guam to extinction zebra mussels clog pipes around the great lakes and speaking from personal experience shred your feet to a pulp in lake travis house cats murder any creature they can get their paws on if they're let outside pushing as many as 70 bird reptile and small mammal species out of existence already the kudzu plant is a climbing vine that smothers and out competes native plants all over the southeastern united states and grows up to a foot a day all of these organisms have found a place to thrive where they didn't originally evolve meaning other organisms haven't had the time to adapt to their presence native organisms don't have defenses against the invaders methods to compete alongside them or even ways to prey on them and the cane toad's particular biology makes it so most of the natural inhabitants of the australian ecosystem don't stand a chance largely because cane toads are extremely poisonous adult cane toads have venom secreting poison glands on each shoulder where a highly toxic milky substance is released when they are threatened if an animal tries to bite at the toad the venom is secreted directly into the animal's mouth and its effect is almost instant the venom which is full of cardiac glycosides causes sodium to build up within the animal cells when this happens in heart cells it completely alters the rhythm of the heart usually making it beat out of control meanwhile potassium builds up between the cells which can cause paralysis this then leads to difficulty breathing convulsions and soon after death a cane toad's poison can kill within minutes this makes the cane toad quite an undesirable snack for most animals especially animals in australia in the cane toad's natural habitat of south and central america some predators like the broad-snouted caiman have evolved mechanisms to block the action of the poison but similar predators in australia have not had time to keep up their end of the evolutionary arms race freshwater crocodiles in australia are experiencing mass die-offs due to the very same toad a study conducted in 2008 saw 77 of freshwater crocodiles die in a period of three years directly following the inland progression of cane toads from the mouth of the victoria river the pace of their deaths exactly matched the pace of the toad's invasion but all hope is not lost for the crocodiles eventually the high death rate may naturally select for crocodiles that have a higher tolerance to the toad toxin this is already being observed in some black snake populations that have been hit hard by the cane toads and other animals are adapting too in even freakier ways australian water rats have learned to flip cane toads over to carve out and eat their hearts with surgical precision avoiding any toxins in turn this could have a positive effect for other native animals with enough time maybe there is hope that australian animals can fight back but unfortunately it's not just the adult cane toads that are the problem even the eggs and the tadpoles are poisonous which if ingested by vertebrate predators like fish and turtles can be fatal and this is no small threat cane toads don't just lay a few eggs they lay an apocalyptic amount of eggs and their toxicity added to their sheer numbers is creating a completely unexpected evolutionary event the life of a cane toad begins within an egg one cane-toed female can lay up to forty thousand eggs at a time that's a lot of eggs but usually when an animal has so many offspring they don't expect many of them to survive but the problem with the cane toads in australia is that basically all of them do survive these tiny black dots speckled down the string of eggs soon will hatch into tadpoles and the pond in which they live will become full to the brim completely blackened with them killing most predators that try to eat them these tadpoles gradually develop forelimbs and hind limbs reabsorb their tails while their gills disappear and their lungs develop once metamorphosis is complete armies emerge onto land as young toads and these armies are only getting more formidable between the 1940s and 1960s cane toads expanded their range by about 10 kilometers per year but today cane toads are moving west at a rate of 50 kilometers a year why are they so much faster now than before at first researchers thought that the toads might somehow be slipping onto trucks and hitchhiking across the country to find out for sure they strapped tiny radio transmitters onto the toads and what they found shocked them the toads were not hitchhiking but were themselves traveling at an alarming rate up to 1.8 kilometers a night far further than any other frog or toad ever studied could this ever accelerating takeover be a result of the army of toads evolving into a faster toad right in front of our eyes while researchers can't go back in time to race modern toads with the first toads brought over from hawaii what they can do is look at preserved specimens of toads from decades ago and what they found is that over a 60-year period australian cane-toad's legs have grown over 25 percent and scientists soon realized that the modern cane toads with the largest legs are those on the western front the first toads to arrive in a new area later waves of toads have shorter legs the cane toads that are able to spread farther and faster have much less competition and thus there is an adaptive advantage in doing so the cane toads were always spreading fast but now they are evolving to spread even faster this is all pretty worrying where we used to think vertebrates can't really evolve on such short time scales the cane toad is proving that they absolutely can if the conditions are right and for invading organisms whose populations explode very quickly this rapid evolution is all the more likely and all the more dangerous but the intense competition between the toads that's driving adaptation has an upside the toads are quickly evolving a taste for themselves they've become so numerous that their only natural predator is other cane toads and while scientists have observed cannibalism evolving in animals before they've never seen it evolve so quickly adult cane toads can be seen eating smaller toads but it's their tadpoles that are doing most of the cannibalizing researchers found that a handful of more developed tadpoles can devour 99 of the tiny hatchlings that emerge from the tens of thousands of eggs in a single clutch so in this instance their immense numbers and rapid evolution is helping to put a cap on their numbers but short of the cane toads eating each other out of existence is there anything we can do to stop them australians understandably want the cane toads gone but unfortunately there's no great way to round them up and kill them the government community groups and frustrated individuals do their best to cull them but it's not easy and not always humane the best thing is to get rid of them get a big stick and hit a method the current guidelines on the most humane way to kill cane toads is to stick them in the freezer some groups try to trap large numbers of toads using speakers to play the cane toad's song to lure toads to it other people just straight up shoot them with air rifles hit them with golf clubs or run them over in their cars when i'm driving a car i have no hesitation of running over them whatsoever there are even toad busting militias that make it their mission to kill as many of the toads as possible but there are too many toads in australia to eradicate by simply removing individuals that's why some want to take a more intentional approach researchers are trying to genetically develop a cane toad that can only produce male offspring using something called a w shredder gene drive [Music] the zw sex determination system is a chromosomal system that determines the sex of offspring of animals like birds some fish some reptiles and the cane toad a z and a w chromosome will give you a female and double z chromosomes will give you a male this is sort of the opposite of the mammal system where the heterozygous xy gives you a male and the homozygous xx a female and in the zw system it's the egg that determines the sex of the offspring unlike the xy system where it's the sperm a w shredder toad is a toad who's been gene edited so that all of its w bearing eggs are defective that leaves just z-bearing eggs so when the male adds his z-chromosome to that you get only z-z offspring meaning you get only male offspring and if the w-shredding gene is located on the z chromosome then this shredding gene can be inherited with enough gene shredder toads in the environment the number of females will be greatly reduced and a male dominated population would be incapable of effective procreation some may argue against this technology saying we have clearly already messed with nature enough but at this point when the damage has already been done and the toads march on we don't have the luxury to not intervene we as a species already are playing god whether we like it or not so we might as well get good at it we might as well do it in a well researched calculated way to undo some of the damage we have done but despite their destruction we can be grateful for the cane toads for one single reason they are the subject of the single greatest cinematic experience a person could ever have this whole video was inspired by a memory cemented in my brain from 10th grade biology of watching the most hilarious documentary i have ever seen perhaps you too have a distant memory of a cane toad named dairy queen inexplicable camera angles amazing interviews grown men singing songs in the shower about cane toads while they stalk him psycho style all textured with 80s synth and incredible jingles [Music] it feels like a mockumentary but it's all real like a love child of national geographic and monty python the cane toad problem is obviously an awful thing but sometimes in the face of a terrible situation all you can do is laugh and in all seriousness it's a powerful piece of science communication this film's been cemented in my brain for 15 years after all as i was trying to reminisce on this magical film i wondered if i would even be able to track it down and to my great surprise and delight i realized it's on curiosity stream in its entirety i almost could not believe my luck if you haven't seen it go watch it now you will not regret it and if you're like me and watched it years ago go re-watch it i promise it's just as funny now as it was back then and make sure to watch it on 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Channel: Real Science

Views: 1,327,655

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Id: tuX5vgH-Rdo

Length: 18min 7sec (1087 seconds)

Published: Sat Feb 19 2022