Thanks to Brilliant for supporting this episode
of SciShow. Go to Brilliant.org/SciShow to learn how to
take your STEM skills to the next level. [♪ INTRO] Snake venoms are some of the world’s deadliest
substances. So snakes have to be super careful with them. I mean, if you have giant muscles, you don't
want to punch yourself in the face. And obviously, if you have potent venom, you don't want to accidentally bite yourself…
or, so you’d think. But actually, in most cases, if a snake bites
itself, it's pretty anticlimactic. We've known this for a long time. Over the centuries, a not-so-small number
of perhaps ethically-questionable scientists have found themselves overcome with morbid
curiosity. So they’ve injected snakes with their own
venoms to see what would happen. And, the short answer is usually: very little,
if anything at all. Most venomous snakes simply aren’t a danger
to themselves, even though, in other animals, their venoms
do some serious damage. Snake venoms are full of toxic peptides and
proteins, molecules that cells make that cause all sorts
of horribly, horribly unpleasant things. Like, neurotoxic venoms mess with neurons
and keep them from sending signals properly. And that means, at their worst, they can cause
life-threatening paralysis. Meanwhile, hemotoxic venoms do terrible things
to your circulatory system, like preventing blood clotting and causing
uncontrolled bleeding. Some snakes even wield cytotoxic venoms: ones that kill cells and can cause parts of
your body to simply die. All of these toxins tend to do their nefarious
work using elements of cells that are found across vertebrate lineages, and even in invertebrates like bugs. Essentially, you can think of the toxins as
keys that unlock really standardized doorknobs found
in all sorts of buildings. That’s why they’re dangerous to us, even
though we’re not the buildings they’re trying to break into. And why it’s weird they’re usually not
dangerous to themselves, even though they have the same kind of doorknobs. Ok, the analogy might be getting a little
strained, but I think you get the picture. We didn’t figure out how the snakes were
surviving their toxic cocktails until somewhat recently. And, it turns out, they can each have several
strategies. For starters, even though venom toxins tend
to attack really important pieces of our biology, some snakes are able to tweak their versions
of these targets. It’s the molecular equivalent of changing
the locks. For example, since neurotoxins are positively
charged, they’re attracted to negatively charged
parts of receptor proteins on nerves. But certain species of snake have just, you
know, reversed the polarity of their receptors. See that trick isn’t only useful on the
Starship Enterprise! Instead of negatively charged receptors, they
have positively charged ones that literally repel the positively charged
toxins. And this isn’t just seen in venomous snakes
that need to protect themselves. Some non-venomous snakes have similar tweaks
to their receptors, presumably to help stay off their cousins’
menu. Other snakes, like the Egyptian cobra, are
able to tack sugars onto their nerve receptors, which physically block the toxins from reaching
their target. But it’s not always possible to modify the
stuff toxins attack. Changes can mess things up, and remember,
these are super important parts of our bodies, so trying to toxin-proof them could be life-threatening
all on its own. So, some snakes have built-in antivenoms. Biologists have suspected venomous snakes
essentially “leak” toxins into their bodies constantly. This lets their immune systems develop targeted
defenses, much in the same way a vaccine prevents you
from coming down with a disease. But some take this idea one step further. They’ve evolved anti-toxins that they keep
in their bodies all the time. That way, if some of their venom gets where
it doesn’t belong, the most dangerous bits are shut down before
they can cause real harm. For instance, some snakes produce proteins
that bind and inhibit their venom’s phospholipases: enzymes responsible for a lot of the nasty
effects of hemotoxic and cytotoxic venoms. These versatile enzymes can do a range of
awful things, like prevent blood clotting and kill cells. So it’s no wonder that snakes like the short-tailed
pit viper have several different phospholipase inhibitors
in their blood. What’s extra cool about natural inhibitors
is that they could help us develop better antivenoms. Modern antivenoms save a lot of lives, but
they’re not perfect. They’re expensive, only cover a limited
number of snakes, and generally require cold storage, which means it can be hard to get them to
the people who most need them. So doctors would love to find a good alternative, and the snakes’ own natural inhibitors hold
a lot of promise. Before we wrap this up, it’s worth noting
that not all snakes have these built in protections. Some can and have killed themselves with a
misplaced bite. Like, in 2016, Australian researchers witnessed
the unfortunate death of a brown tree snake that bit itself, which suggests that brown tree snakes aren’t
immune to their own venom. And even ones that are may not survive the
bite from other members of their own species, since there can be a lot of toxin variation
between individuals. Like, in 1932, scientists made a couple of
black-tailed rattlesnakes bite each other, and let’s just say that things did not end
well for either rattlesnake. In many cases, though, the animal’s built-in
venom defenses can prevent personal tragedy. So while I imagine it’s super embarrassing
for a snake to accidentally bite itself, most can slither away mumbling “I meant
to do that.” If you liked this episode of SciShow, and
want to learn more about the world around you, you might like the courses offered by today’s
sponsor, Brilliant. Brilliant’s app and website allow you to
learn about math, science, engineering, and computer science at your own pace and
in a really fun and effective way. There’s no memorization or tests or grades,
just really fun, engaging lessons and problem-solving tasks
that you can do anytime, anywhere. So you can hone your algebra skills when you’re
on your break, or settle in on a Friday night for the whole
cryptocurrency course to really figure out what this Etherium stuff is. And as a thank you for watching SciShow, you can get 20% off an annual premium subscription
by signing up at Brilliant.org/SciShow. So if you’re interested, head there to learn
more! [♪ OUTRO]
