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How do snakes swallow animals so much bigger than they are? - Niko Zlotnik - Video học tiếng Anh
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How do snakes swallow animals so much bigger than they are? - Niko Zlotnik
How do snakes swallow animals so much bigger than they are? - Niko Zlotnik
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उपशीर्षक (81)
0:07
How can a bigger tube fit inside a smaller tube?
0:11
This might sound like a riddle,
0:13
but it’s a practical dilemma in our snake-eat-snake world.
0:19
This eastern kingsnake, for example, has a mouthful of a Texas rat snake,
0:25
but the rat snake’s longer than it is,
0:29
so how can the kingsnake possibly swallow it whole?
0:34
This is just one of countless predatory dilemmas snakes have solved.
0:39
Since slithering onto the scene some 150 million years ago,
0:44
evolving length and limblessness out of their ancestral lizard forms,
0:50
snakes have diversified rapidly.
0:53
Their noodly bodies and flexible heads
0:56
granted them access to novel places and prey.
1:01
And today, there are nearly 4,000 snake species,
1:05
spanning habitats high and low, wet and dry.
1:10
All are carnivorous, but their diets range from fish eggs to alligators.
1:17
Jaw-dropping anatomy allows most snakes to swallow their meals whole.
1:23
Because their jaw bones aren’t fused like ours
1:26
but connected by an elastic ligament
1:29
and the bones on the sides of their lower jaws flare apart,
1:33
they can dramatically stretch their maws.
1:37
Reticulated pythons can even achieve 180-degree gapes.
1:43
Sharp, curved teeth also line many snakes’ jaws,
1:48
keeping prey from wriggling out.
1:51
And to prevent suffocation when choking down a big meal,
1:55
many snakes shift the position of their airways’ entrance
1:58
and isolate which rib cage regions they inhale with.
2:03
Pythons are also equipped with stretchy tissue along their jaws,
2:09
enabling them to spread four times wider than their own skulls.
2:15
They’ve been documented using this skill to eat hyenas, alligators,
2:20
and— yes— even humans, whole.
2:25
Their skin might sag after all the stretching
2:28
and it could take weeks to metabolize meals this large,
2:32
but it seems their intestines have special cells for helping digest bones,
2:38
and they can sometimes survive for over a year on just one feast.
2:44
African egg-eating snakes, meanwhile, consume large, intact bird eggs,
2:50
piercing their shells in their esophagi using inward-facing vertebral spines.
2:58
But while many snakes make a show of swallowing things whole,
3:02
crab-eating snakes often pry their prey’s limbs off
3:07
one-by-one
3:09
and blindsnakes decapitate their termite targets,
3:14
probably to prioritize their more digestible bodies.
3:19
Some blindsnakes actually use chemical secretions to repel their prey,
3:26
because it allows them to hang out in ant colonies,
3:30
snacking on their inhabitants without being attacked.
3:33
Their skills have even been noticed by other species.
3:38
Eastern screech owls sometimes place blindsnakes in their nests,
3:43
where they eat the insects that might otherwise harm their young.
3:48
In fact, baby owls with a blindsnake nestmate have higher rates
3:55
of growth and survival.
3:57
The same can't be said for other species.
4:01
Turtle-headed sea snakes scrape fish eggs off coral reefs.
4:06
And cat-eyed snakes hunt red-eyed tree frog eggs.
4:12
However, even as embryos,
4:14
the developing frogs can sense an attacking snake’s vibrations
4:19
and may prematurely hatch to escape.
4:22
It’s a sacrifice— but at least it’s not certain death by serpent.
4:27
Garter snakes, meanwhile, go after western newts
4:32
even though their skin is packed with a potent neurotoxin.
4:37
Just one bite could kill a person,
4:40
but garter snakes swallow the newts unscathed,
4:44
since modified proteins in their nerve cells prevent the toxin from binding.
4:50
Not only that, but since the toxin may remain in their livers
4:54
for weeks afterwards,
4:55
it may even end up lending garter snakes protection against their predators.
5:03
However, snakes more often make their own toxins,
5:08
injecting or spitting venom from specialized glands
5:13
out of grooved or syringe-like fangs.
5:17
Philippine cobra venom is full of fast-acting neurotoxins
5:22
that cause paralysis and respiratory failure.
5:26
West African saw-scaled viper venom is a cocktail of compounds
5:31
that cause profuse bleeding and tissue death.
5:36
And while inland taipans are thought to possess the world's most potent venom,
5:41
they tend to reserve it for quickly killing rodents.
5:46
But we still haven’t answered how smaller snakes can consume bigger ones.
5:53
It turns out that the kingsnake does this with an elegant trick.
5:58
Once it runs out of space in its flexible stomach,
6:02
it stretches and compresses its spine,
6:05
shoving the rattlesnake into a kinked, zig-zag shape within its digestive tract.
6:12
So a post-meal X-ray may look like this.
6:18
Sorry, we know the truth can be hard to swallow.
6:23
Unless, of course, you're a snake.
