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Claws and teeth are one way to catch a meal, but here are six animals that have evolved some pretty unique hunting techniques.

Hosted by: Hank Green

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SOURCES:

Frogfish
http://science.sciencemag.org/content/205/4411/1161
https://www.waikikiaquarium.org/experience/animal-guide/fishes/frogfishes/frogfish/
http://www.critter.ch/Frogfish-Anglerfisch/Teresa_Zuberbuehler_2018_Frogfishes-Southeast-Asia-Maldives-Red-Sea.pdf
http://drs.nio.org/drs/handle/2264/2938

Bolas Spider
https://www.nature.com/news/2002/020624/full/news020617-14.html
https://link.springer.com/article/10.1007%2Fs004420050347
https://www.annualreviews.org/doi/abs/10.1146/annurev.en.39.010194.000501
https://www.researchgate.net/publication/233060388_A_Review_on_Spider_Silk_Adhesion
https://asknature.org/strategy/wings-allow-escape-from-spider-webs/#.W9t5LHo2rs0

Humpback Whale
https://www.sciencedaily.com/releases/2011/06/110624083516.htm
https://www.alaskawhalefoundation.org/research-1/
https://static1.squarespace.com/static/533dfcebe4b0cf4885e5162a/t/534efe4de4b0e7399e106e5a/1397685837754/Sharpe+-+PHD+dissertation+%28SocialForagingOfHumpbacks%29.pdf
http://www.naturalhistorymag.com/biomechanics/082067/as-the-whale-turns
https://www.ncbi.nlm.nih.gov/pubmed/17051544?dopt=Abstract

Pistol Shrimp
http://science.sciencemag.org/content/289/5487/2114
https://www.nature.com/articles/s41598-017-14312-0
https://www.wired.com/2014/07/absurd-creature-of-the-week-pistol-shrimp/
http://www.bbc.com/earth/story/20160129-the-shrimp-that-has-turned-bubbles-into-a-lethal-weapon
https://www.youtube.com/watch?v=KkY_mSwboMQ

Stoat
https://www.bbc.co.uk/programmes/p0074tkf
https://www.youtube.com/watch?v=ODEUK5sB5vE
https://www.countrylife.co.uk/nature/13-things-never-knew-weasels-taking-rabbits-squeezing-rings-172489
http://karlshuker.blogspot.com/2011/02/mesmerising-mustelids-and-dance-of.html
https://www.gamekeeperstrust.org.uk/media/uploads/cat-264/gwct-stoat.pdf
https://books.google.com/books?id=EwmCBgAAQBAJ&pg=PT70&lpg=PT70&dq=Stoat+skrjabingylus+dance&source=bl&ots=h9FQod4DyX&sig=mOzJTES_wbd40sdMhhaBcUsp85E&hl=en&sa=X&ved=2ahUKEwjzzMfGraXeAhUK5YMKHXdaC8sQ6AEwFXoECAEQAQ#v=onepage&q=Stoat%20skrjabingylus%20dance&f=false
https://academic.oup.com/jmammal/article/88/4/946/909918
http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU320666
https://books.google.com/books?id=5ae9c7GO_cUC&lpg=PR9&ots=M9qvan5CTA&dq=dance&lr&pg=PA120#v=onepage&q&f=false
https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-7998.1971.tb01309.x

Human
https://www.nature.com/articles/nature03052
https://news.harvard.edu/gazette/story/2007/04/humans-hot-sweaty-natural-born-runners/
https://slate.com/culture/2012/06/long-distance-running-and-evolution-why-humans-can-outrun-horses-but-cant-jump-higher-than-cats.html
https://www.businessinsider.com/how-humans-evolved-to-be-best-endurance-runners-2018-3
https://www.theguardian.com/science/blog/2018/mar/14/why-humans-are-optimised-for-endurance-running-not-speed
https://www.npr.org/2010/07/19/128626037/for-humans-slow-and-steady-running-won-the-race
https://www.youtube.com/watch?v=826HMLoiE_o

 (00:00) to (02:00)


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(Intro)

In the animal kingdom, it's eat or be eaten.  So over millions of years, predators and prey have existed in a perpetual evolutionary arms race to escape the jaws of death, whether by starvation or by, you know, the jaws of the creature that wants to consume them.  That means there are quite a few animals who have developed the skills and anatomy to hunt for their food in some pretty novel ways beyond just speed and sharp claws.  We're talking about things like manic dancing and bubbles.  Yeah, bubbles.  So here, my friends, are six animals with some pretty weird hunting techniques.


 1: Frogfish (0:48)


Frogfish, despite the name, have nothing to do with frogs.  They are fish, though, and they don't often swim.  Instead, they use their fleshy fins to walk along the sea floor, and also, unlike most fish, they actually fish for their meals using both camouflage and a baited rod.  The camo part is called aggressive mimicry.  They blend in for the purpose of predation, not protection.  Frogfish are almost impossible to spot on the reefs, rubble, or sand where they lay and wait, but to make sure their meal comes close enough that they don't have to like, do anything to go get 'em, they also have a modified dorsal fin spine, which can act as a fishing rod with bait.

The lure, called an esca, is unique to each species and can look like anything from a tiny shrimp to a worm to something just vaguely fishy.  When another fish gets too close, the frogfish rapidly opens its jaws, expanding its mouth cavity to up to 12 times its original volume in less than 10 miliseconds.  This creates suction that pulls the nearby water in, including whatever's in that water, like a fish.  The bait even works in the dark.  That's because lots of marine creatures are attracted to vibrations in the water, even when they can't see what's making them, but there is at least one species with an esca that glows, thanks to light-producing bacteria, and in the not-so-rare event that the frogfish's lure actually gets nibbled off, it can regenerate it in 4-6 months.

 (02:00) to (04:00)


 2: Bolas Spiderss (2:14)


Female bolas spiders are also aggressive mimics.  They lure male moths to their doom by pretending to be a potential mate, but that's not what makes their hunting strategy so awesome.  Bolas spiders are technically classified as orb-weaving spiders, but unlike their relatives, they don't actually weave any webs.  That's because the moths they prefer to eat have wings that are covered in detachable scales and those are what often ends up stuck to a web rather than the whole bug.  

So instead, these spiders take a string of their silk and excrete a big glob of glue onto the end of it that's capable of sticking to the moths' bodies.  This weapon is how they got the name 'bolas spiders'.  It looks a lot like a bolas, a ranged weapon consisting of heavy weights connected by a long strip, but they don't throw their bolas like people do.  They swing them to snag their targets, and that means their reach is limited by the length of the string.  So to ensure they get enough to eat, the spiders infuse their bolas with pheromones that smell like female moths.

Each species of bolas can mimic the scent of at least one species of moth, sometimes two or three, and some can vary the species over the course of a night to maximize their potential catch.  When the right male moths catch a whiff, they head straight for the bolas expecting a potential mate.  Instead, they get eaten by a spider.


 3: Humpback Whales (3:33)


Humpback whales don't have any fancy weapons to catch their meals with, but they do have big old brains, so instead, they use nets made of bubbles to trap their prey.  Humpbacks are baleen whales, which means that instead of teeth, they have curtains of bristles that act as strainers so they can feed on small fish, krill, and other tiny ocean creatures.  Since they're some of the largest animals living on Earth, they have to eat a lot of this teeny tiny food, and it turns out corralling their prey into dense swarms with the power of bubbles is a super efficient way to do that.  

 (04:00) to (06:00)


To us, bubbles might seem flimsy, but to a tiny animal underwater, a wall of air bubbles acts as a physical barrier that's tough to see through and basically soundproof.  So these whales create bubble nets and then fly up through the bottom to gulp a big mouthful of trapped and perhaps confused prey.  The bubble nets are made by teams of two or more whales and can be over 40 meters in length, though to really pack the prey in, they can be as small as two meters across. 

Most do spirals to create their nets and then swim up through the middle to take big gulps, but a few animals in Southern Alaska do a weird double loop.  They do a single loop to make the corral and then smack the end of their tail against the water's surface, which scientists think might stun a lot of the prey they just gathered.  Then, the whales make a big upward lunge to actually eat them. 

Making intricate small circles is no easy feat for an animal that's at least the size of a bus, but humpback whales have some anatomical advantages that make them highly maneuverable.  Their long pectoral flippers, which are the longest of any whale, generate a lot of lift, and they're covered in large bumps called tubercles that reduce drag to help them grip the water better, giving the whales a remarkably tight turn radius for an animal so big.


 4: Pistol Shrimp (5:16)


 There's another marine animal that uses bubbles to hunt but in a very different way: the pistol shrimp.  Their bubbles create literally stunning shockwaves.  Instead of regular pinchers, pistol shrimp have a giant claw that can be almost half as long as their whole body.  The immobile, larger part of this claw acts like a socket for a perfectly shaped part of the smaller swinging piece. 

The shrimp can pull back this piece and lock it into position to store up a bunch of elastic energy.  Then, to strike, it just releases and closes the claw.  That causes the water inside the socket to fly out at speeds exceeding 100km an hour, fast enough to cause a massive drop in the moving water's pressure.  That super low pressure allows a bunch of tiny microbubbles already present in the water to expand and quickly combine to make one big bubble, but in 1/1000th of a second, this bubble collapses due to the pressure from the water around it.  

 (06:00) to (08:00)


This is called cavitation and it creates a brief but intense heat, a flash of light, and a powerful shockwave that can outright dismember some small creatures, and it's more than enough to stun the small fish, crabs, and other shrimp that the pistol shrimp eats.  The shrimps also use the sound of snapping to communicate with one another, so much so that when you go diving in areas where they live, you can often hear a constant cacophony of their snaps.

In the unfortunate event that the shrimp loses this stun gun of a claw, it can grow it back, kind of.  The other pincher actually transforms into one over several molts, ensuring the shrimp gets its stun gun back as quick as possible.  What a handy skill!


 5: Stoats (6:51)


Stoats are a kind of weasel found all over the Northern hemisphere as well as New Zealand, where they're an invasive species.  They are voracious hunters known to attack prey up to 10 times their size and they're particularly fond of rabbits.  Stoats have the endurance to chase rabbits down, but they have another, more entertaining way to catch 'em: dancing.

The deadly dance of stoats has been observed for centuries and has made the little predators notorious, especially in Europe.  I mean, we call it a dance but they're really just bounding around like little maniacs flipping over themselves right in front of a rabbit.  The rabbit seems to be so confused by the dancing that it just sits there, which, to be fair, you probably would too if a stranger wandered up to you and like, started breakdancing or something.

That allows the stoat to get closer and closer and closer until it's near enough to leap on the rabbit's back and bite it in the neck.  For smaller prey, the bite would sever the spinal column, but for rabbits, it takes several bites to do enough damage to nerves and blood vessels to make the animal die from shock.  While this dance hunting has lots of anecdotal evidence to back it up, not all scientists are convinced that the stoats dance with the intent of confusing their prey.

 (08:00) to (10:00)


They're sometimes observed dancing without a rabbit in sight, so some think it's just a form of play or even a side effect of a parasitic nematode that lodges itself behind the stoats' eyes.  There haven't been any studies directly confirming the dancing behavior comes from infection, though, and dancing for fun doesn't mean they don't dance for their dinner, too.  Proponents for the dance hunting hypothesis point out that just because you don't see a bunny doesn't mean there isn't one there.  Humans don't have the stoats' keen sense of smell or hearing and a target could be visible to them that's obscured from a person's elevated point of view.


 6: Humans (8:36)


Finally, we turn to what might be the most successful hunter in the entire animal kingdom: homo sapiens.  Humans, of course, have developed far more sophisticated hunting tools than other species, but when you strip away all those, there remains one technique that's actually still pretty weird for the animal kingdom: running or rather, the ability to run prey to the point of exhaustion while barely breaking a sweat.  Proverbially, anyway, because we definitely do sweat when we do it, and that's one the traits that allows us to hunt this way.

About two million years ago, long before the first bow and arrow, the ancestors of modern humans started evolving the adaptations needed for endurance running.  This includes stretchy tendons in the legs and feet, which can store and then release tension with each step to make our strides more energy-efficient.  They also developed bigger glutes and a flexible waist, which allows us to keep balance while we throw ourselves forward, but as great as it is to be able to run far, it means nothing if there's no way to dump all the excess heat that builds up from working out that much.

That's probably why we sweat so much.  We have 2-4 million sweat glands that ensure we can sweat away excess heat while on the move.  It may also be why we're nowhere near as hairy as our relatives.  Less fur makes our sweating more effective than other species that sweat, like horses.  A lot of other mammals cool down by panting and that, while effective,  can't be done while sprinting, because short shallow breaths don't provide enough oxygen for that kind of exertion, so being able to disperse heat well while running allows humans to chase down fast prey in sweltering conditions when most other predators would have to rest, and even when that prey can sprint fast enough to get well ahead of human hunters, they soon have to stop to catch their breath and cool down, giving people a chance to catch up.

 (10:00) to (11:39)


A few cycles of sprint-rest-sprint and most animals overheat or are just too exhausted to flee again.  Some cultures in the world today still use this strategy to catch their meals, continued proof that humans are pretty awesome hunters with or without our projectiles and pointy sticks, and if you're looking to improve some of your own food-making skills, you might be interested in this SkillShare class on knife skills by Chef Elena Karp.  

Like, did you know that most of us have probably been holding knives wrong our entire lives and that there is, in fact, a way to dice an onion so fast you don't have time to cry?  Karp teaches you everything you need to know to chop vegetables like a pro and without chopping your own fingers in the process and if you already know how to slice and dice, SkillShare has plenty of advanced culinary classes, too, along with more than 20,000 other classes about practically anything you can think of.  Right now, SkillShare is offering SciShow viewers two months of unlimited access to all their classes for free.  Just check out the link in the description.

(Endscreen)