Bloody Amazing Facts About Vampire Bats

Vampires. They’re in all kinds of spooky stories — and
certain Young Adult fantasy romance novels. There may not be undead, blood-sucking humans
walking around. But blood-drinking mammals do exist, in the
form of vampire bats. Surviving on a diet of only blood, also known
as hematophagy, isn’t easy, and vampire bats are one of the few mammals that have
evolved a thirst for blood. Along the way, they also developed some useful
techniques to help them survive. To be clear, vampire bats don’t exactly
suck blood. Instead, they drink blood using the physics
of capillary action, where a liquid can move through a narrow tube or cylindrical space
— often against the downward force of gravity. Vampire bats have special grooves on their
tongues — which, along with their lower lip and incisors, can create a tube-like shape
that easily wicks up the liquid. They do make a lapping motion with their tongue,
which helps speed up the process, but it isn’t necessary for capillary action to work. Another thing that helps keep the blood flowing
is the bats’ saliva. Vampire bat saliva contains a protein called
desmoteplase, which researchers nicknamed Draculin. It acts as an anticoagulant to stop blood
from clotting. Researchers have actually isolated this protein
from vampire bat saliva in the hopes of turning it into an anti-stroke medication — since
it helps stop blood from clotting, it might also be good at preventing blood clots in
human brains. So when a vampire bat bites into a juicy blood
vessel, the proteins in the saliva keep the animal’s blood free-flowing for a big meal. And vampire bats need a big meal every time
they feed. Blood isn’t a very rich food source. It’s mostly made up of water, with small
amounts of protein, sugar, and trace minerals. It’s completely lacking in fat. And animals tend to need fat, which is a major
type of energy storage in a balanced diet. So vampire bats need to drink about half their
weight in blood every day to get enough nutrients to keep their metabolism running smoothly. Since that means they’re taking in a lot
of water, their digestive and excretory systems quickly filter out water and leave the proteins,
sugars, and minerals to be digested. In fact, vampire bats will often start urinating
even before they’ve finished feeding, just to keep things flowing. Finding food takes some special skills, though. Like other bats, vampires use echolocation
to fly around and look for prey. They also have a keen sense of smell and decent
eyesight. But the wrinkly faces of vampire bats have
specialized nerve fibers loaded with proteins that allow them to detect the infrared radiation
given off by warm-blooded animals. Once they find something to eat, the three
known species of vampire bats all have unique feeding behaviors. Common vampire bats feed only on blood from
mammals, and they prefer livestock. So these bats evolved ways to quickly maneuver
on the ground and reach their prey more easily. They have strong hind leg muscles and elongated
thumbs at the tips of their wings, which they use to jump around. They’re agile enough to escape from ground
predators. Hairy-legged vampire bats, on the other hand,
feed exclusively on bird blood and hunt from the tree tops. They jump onto unsuspecting birds from above,
and usually try to bite the bird in the cloaca — the multipurpose exit point for a bird’s
digestive and urinary tracts, and also the place where it keeps its reproductive organs. For some reason, the birds tend not to like
this very much. So, to stop the bird from fighting back or
knocking it off, the hairy-legged vampire bat uses the big bony spurs on its ankles
to help it hang upside-down and latch onto its prey. White-winged vampire bats feed on both mammals
and birds, but they evolved a few tricks to help them feed on chickens. Sometimes, the bat lands on the chicken’s
back, so the chicken thinks the bat is really a mounting rooster. So the chicken just crouches down, giving
the bat access to its neck for feeding. Other times, the white-winged vampire sneaks
up from underneath the chicken and nuzzles against the brood patch — a featherless spot
of skin normally used to keep chicks warm. The chicken thinks it’s being nuzzled by
a baby chick, and lets the vampire latch on and start drinking blood. With all these complicated feeding techniques,
you’d think vampire bats would have no trouble finding a meal. But sometimes they don’t get enough. Luckily for the bats that don’t find enough
food, vampire bats live in large colonies that can contain thousands of bats, and they
take care of each other using a behavior called reciprocal altruism. Often, one bat will sacrifice their own needs
for another, with the assumption that they’ll be helped in return in the future. The main way they do this is very appetizing:
they regurgitate blood to share with bats that weren’t able to get a meal. Bats who’ve shared blood meals in the past
get larger donated meals in return, compared to more selfish bats. So yes: like Dracula, vampire bats are skilled,
blood-drinking hunters. But they also have to be extra nice to each
other to help their colony survive. Thanks for watching this episode of SciShow,
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100 thoughts on “Bloody Amazing Facts About Vampire Bats

  1. Today I learned Vampire bats are socialist. I'm sure there's some joke here about how the right is less caring than literal bloodsuckers, but I'm no comedian.

  2. 2:01 Did you say that vampire bats can see in infrared?! Please do a video on this! Infrared detection is very rare in living things!

  3. So basically "They jump onto unsuspecting birds from above and usually try to bite the bird in the ass- and for some reason the birds tend to not like this very much" 😀

  4. 0:20 "Vampire bats are one of the few mammals that have evolved a thirst for blood." And politicians — don't forget about them.

  5. So, basically vampire bats pretend to ravish their prey and make meals of the ones who fall for it?

    Now that would be a fascinating twist ending to Twilight. Maybe work in the other technique and have a mysterious lost baby suck from some sucker who tries to cuddle it. Bonus if she actually tries to give it suck, and gets sucked in a way she absolutely did not expect.

  6. How nice of bats to share with one another… Though in a gross way though, basically puking and then exchanging puke. Blood/puke is bat currency xD

  7. I remember there being mentioned something about scientists finding butthair too much of a taboo to research.

    I'm confused.

  8. why the fuck did this evolve? if blood is lacking in nutrients why do they do this? surely huntibg for ibsects and smaller anumals is more rewarding? btw… for "some reason" the birds dont seem to like this very much…. lol

  9. Why the fuck would we want a stronger anticoagulant than heparin and acenocumarol? Those still work pretty good and they have a pretty high hemorrhagic risk even in people with high clotting risk. Using this protein from bats would increase that hemorrhagic risk even more. Might be a classic case of the remedy being worse than the disease, if you ask me.

  10. So not only this horrifying creature will creep on me to suck my blood at night, it will pee on me first ?!
    Why life is so unfair ?!

  11. Vampire bats are so nasty. Of all the species humans have driven to extinction, why couldn't it be an environmentally worthless pest like the vampire bat. I can't see any ecological reason, that any species would need some parasite biting and drinking blood from their cloaca, and they do feed on humans as well. There are many bats that provide a large benefit to nature, especially ones that eat insects and even fruit bats, but vampire bats are not one of those with any benefit or vital role. They are just disgusting.

  12. Wait, if blood contains no fat, even drinking half their body weight in blood won't be sufficient to provide them with fat?

    I'm also curious how blood eating animals evolved to be.

  13. Vampire bats have a high metabolism, so if they don't feed every other day, they will die. One other cool thing they will do is adopt the orphans in their colony to keep the young alive. I think that's a pretty neat thing you've forgotten to mention!

  14. When you're a horny chick waiting to be mounted but then realized it's another on of those annoying bats wanting to drink your blood again.

  15. I'm curious about the video's affirmation at 1:29 that blood "[is] completely lacking in fat…" If this is so, how do people develop atherosclerosis?

  16. Soo… hairy-legged vampire bats are truly the worst… and chickens are really stupid. That's my education for the day!

  17. How does it get to the blood? Does it work like an insect proboscis or do they rip out an opening and funnel it with their tongue?

  18. Draculin. Really? Pikachurin, Sonic Hedgehog, Dracorex Hogwartsia, and now Draculin. Sigh, why must scientific findings be named by nerds?

  19. Michael: says a species of vampire bat bites and sucks the blood from bird genitals
    Michael: "…for some reason the birds tend to not like this very much."

  20. Some biologists consider vampire bats venomous because of the unique nature of their saliva. Vampire bats are also reservoirs for rabies.

  21. Am I the only one here who thinks that vampire bats are kinda cute??? (I mean yes they also look kinda scary with the fangs and stuff but at the same time they look kinda cute)

  22. The fact that vampire bats will share blood (via regurgitation) with others who don't have enough is simultaneously disgusting and heartwarming.

  23. what an amazing creature, Vampire Bats have some amazing creature power and instincts inside of their small bodies, creatures of the night

  24. This was such a clear, concise, to the point presentation with no excess nonsense
    Edit: I sound like a fucken school teacher

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