We Can't Live Without You | Synanthropic Animals

[Music] if you see a spider in your house hopefully you don't reach for a shoe you carefully caps the little fella and put it outside because that's where spiders belong well actually the best thing you could do is leave it alone it turns out that many of the spiders you find in your home have adapted to living in houses and they might actually die if they're put out they are what biologists call sin anthropic species organisms that live closely with humans and benefit from doing so these animals aren't domesticated but they still depend on humans to some degree and some of them would straight-up die out if we did so you could say the six animals on this list love us a little too much meanwhile our feelings on them vary considerably we are not always as appreciative of helpful sinan throats as we should be like those sweet little spiders the cow-house spider is found all over the world though not because it's particularly Hardy or particularly able to disperse it's because it hitchhikes on our stuff the species probably originated in South America but we're not quite sure they've been hanging around humans for so long that by the time scientists got around to describing them they'd already made it as far as Germany and pretty much everywhere they live they are almost totally dependent on us and our warm cozy buildings like other species of house spider they've gotten used to the very specific conditions inside human homes and other structures namely a constant climate and believe it or not the limited access to food and water only somehow spiders can survive outside and warmer climates even then they are almost exclusively found on man-made structures like rubble piles and bridges which give them sheltered secure places to hide and in colder climates they don't stand a chance so assuring them outside has the same effect as just squishing them but altruism isn't the only reason you should reconsider evicting your eight-legged roommates inside these spiders can act as effective pest control collectively all the world's spiders consume something like 600 metric tons of insects every year some estimates suggest that a single spider can eat up to 2,000 insects annually though how spiders are probably less gluttonous than that since indoor environments don't contain quite as much food they do have an impact on common household bugs though things like flies mosquitoes cockroaches you know bugs you like even less than spiders and for the most part they stay out of your way while they manage these pests for you in a way you could say that purple martins like humans because humans like them this large species of swallow lives primarily in the eastern half of the United States it's not hard to see why people enjoy them they're colorful they have a pleasant song and their acrobatic fliers which makes them really fun to watch plus if that's not enough they also help deal with pests they like to eat invasive fire amps and insects that can damage crops and they're thought to fend off crows and blackbirds which have the annoying habit of digging up freshly planted seeds so people are pretty fond of them so much so in fact that throughout the eastern US it's customary to put out nest boxes and encourage the birds to hang around and digitus people may have also done this and if that's true then the practice has been going for a long time long enough that Martens have come to rely on those human provided homes before us they made their nests in abandoned woodpecker holes and other hollows we've gotten rid of a lot of dead trees where they would have made such homes and invasive birds like starlings and sparrows have moved into many of the natural sites that remain so experts think that if human beings suddenly stopped providing them with nest boxes there's a good chance the birds would die before they could revert back to their natural nesting habits in the eastern US anyway purple martins are also found west of the Rocky Mountains and they're the birds I haven't had people providing them nest sites for centuries so they still nest the natural way and they can probably ensure the species continues on with or without us some beetles may seem kind of gross but they're helpful to have around because they do a job you likely do not want to do they help break down large piles of animal waste making them less offensive and less prolific and juicy are really curious they do this by actually eating the poop but not just any poop will do dung beetles are specifically looking for protein rich sources of nitrogen which comes from the gut wall of the pooper so they're kind of picky about which piles they dine on luckily enough for the people of Iceland at some point in the past the northern dung beetle hitched a ride on to the island with human colonists and their livestock prior to that these beetles lived mostly in the northern parts of continental Europe and Great Britain so weather-wise Iceland makes sense but they can only breed in the dung of large mammals like cows and horses before humans live there Iceland didn't have any animals that fit their needs now if domesticated animals were suddenly to vanished from Iceland the beetles couldn't just move on to another animals poop they would disappear as well and if the beetles weren't there those giant poop piles would stick around a lot longer so those early ice lenders might not have meant to bring dung beetles with them but it's kind of a good thing they did unless you are very very lucky you have almost certainly done battle with granary weevils even if you think you've been very very lucky that may be because you're not looking close enough granary weevils are tiny and easy to miss adults are a mere three to six millimeters long though at least they are dark in color - larvae are even harder to spot they look kind of like the grains of rice they are often found living in and their presence in our dried grains is no coincidence thanks to evolution that's where they live now like the common house spider granary weevils can be found all over the globe they probably evolved on the eastern slopes of the Himalayas but they've been with humans for a long time and somewhere along the way they adapted to living with us so much that they can't survive without us anymore like they lost the ability to fly their wings evolved into hard fused structures that help protect them from being bumped around inside large bags of food and without wings riding along in bags of rice or other dry food stuff is the only way they can move from place to place so they have become entirely dependent upon us for their dispersal that also means that your weevil problem didn't happen like in your house the eggs and larvae actually arrived tucked away inside that bag of rice you bought so YUM and if humans weren't constantly acting as unwitting weevil chauffeurs these bugs would probably die out in fact some species of granary weevil have never been found outside of human food storage areas if you're fond of wolves you are probably too well acquainted with the webbing clothes moth even if you've never seen one you've probably seen their handiwork the mobs themselves are kind of innocent looking though at 4 to 9 millimeters they're a bit larger than a granary weevil but not much and they're a pleasant buff color with a tuft of red hair on their heads kind of like a flying sweater eating version of Eddie Redmayne webbing clothes moths are famous for destroying wool but they will eat any animal fiber including silk leather fur and feathers and you might think that they've had a long history with humans since they're so good at making neat little holes in your sweaters and scarves but they've actually only been hanging out in human homes since the invention of indoor heating so sometime around the latter half of the 18th century originally this moth is thought to hail from Central or southern Africa where the climate is warm and dry and human homes and colder climates weren't really its kind of place at first but then we started heating our houses artificially and the bugs saw an opportunity today web enclose moths living outside of Africa are rarely found outdoors and when they are they're probably there by accident they either prefer living in homes or have changed to some aspects of their biology to make it so they have to so perhaps the most effective way to rid a house of these pests would be to shut off the heat except you can't do that because the moths ate all your sweaters the mosquito Anopheles alba tarsus probably became a sin and throat opportunistically while other mosquitoes are still breeding in stagnant pools like a bunch of suckers these South American mosquitoes seem to be developing a preference for irrigated lands especially rice paddies researchers studying mosquitoes on a Brazilian rice farm had a hard time finding them in nearby forest habitats suggesting they either prefer man-made wetlands or don't survive as well outside of them which could make sense this habitat not only provides a place to breed it also ensures the animals have plenty of food nearby and by food I mean of course our blood in case you need a refresher female mosquitoes use the protein in blood to make their eggs so without blood they do not do so well now this particular species isn't fussy about what kind of animal blooded imbibes so it's not specializing on us but large populations of humans probably look like a nice banquet to them and partly because of that they now stick to waterways we create which is a big problem as if stealing our blood wasn't annoying enough these mosquitoes can also carry the parasites that cause malaria in fact in some parts of Brazil they are the primary malaria vector not only are they taking advantage of habitats we've created they're also sickening and sometimes killing the people who create those habitats and that is just the kind of sin and probit relationship we do not feed as you can see sinan throats run the gamut from helpful pest eaters to dangerous disease spreaders so what they have in common is that they are incredible opportunists they didn't need to be domesticated to somehow figure out that throwing their lot in with humans was a great survival strategy we've unwittingly provided them with comfortable warm places to live plenty of food and you know if they get bored lots of good YouTube videos to watch and because of that they will likely be a part of our lives for a long time thanks for watching this episode of scishow if you want to learn more about how our species has influenced other organisms you might want to check out our episode on animals that have evolved at hyperspeed and to catch every episode of scishow be sure to subscribe and ring that notification bell lake is 2014 [Music]

Channel: SciShow

Views: 200,400

Rating: 4.9589357 out of 5

Keywords: SciShow, science, Hank, Green, education, learn, synanthropic, cohabit, dung, spiders, mosquito, weevil, bird, martin

Id: BRovJG6sGlQ

Length: 10min 27sec (627 seconds)

Published: Sun May 17 2020