For some people, this room might be the scariest place on earth.

Behind these black curtains are deadly spiders, hundreds of them.

And what we're gonna do is poke them, make them angry, and then suction the venom that appears at the end of their really long fangs.

Well, this is about as close as I ever want to get to a funnel-web.

And we're doing it for a very good reason.

This is a funnel-web spider. They live around Sydney, which just happens to be one of Australia's biggest cities.

And they build underground burrows, which are distinctive, because of the funnel shape of the web at the entrance, hence the name funnel-web.

But because they feel safe in dark, cool places, they can end up having unexpected run-ins with people.

What happens is during the breeding season, the male funnel-web will leave his burrow, and he moves around only at night, looking for the females.

But sometimes he gets, you know, a bit adventurous, and he might leave his burrow, go too far from it.

And so in the morning, once the sun starts to come up, he's too far from his burrow to go back to it, so he kind of has a little freak out, and has to find somewhere temporary to hide out during the day.

And so what he'll do is he'll head into a nice, dark, safe spot, like a pile of clothing, or a pair of shoes on the ground.

You'll often see Australians bang their shoes together before putting them on just in case.

If you are unlucky enough to get bitten, it'll be painful, because their fangs can be up to one centimeter long, that's longer than many snake fangs.

And the venom delivered is fast-acting and deadly.

We only milk the males, because they are six times more toxic.

So the males venom actually produces a higher quality anti-venom.

So the fastest time that we've seen an adult die from a male funnel-web spider was about 76 minutes, so just over an hour.

So it's a very fast-acting, rapid venom.

Ideally, you wanna stay calm, still, and apply a pressure immobilization bandage, and then get to the hospital as soon as possible.

The venom contains a mixture of proteins, notably the delta hexatoxin.

As it travels through your bloodstream, you'll begin to sweat, twitch, salivate, and get goosebumps.

This is because the venom acts on nerve cells, neurons.

Under normal conditions, neurotransmitters trigger neurons to open ion gates, and positively-charged sodium ions flood in.

The dramatic swing from negative to positive triggers the release of neurotransmitters to the next neuron, and then the ion gates close, and the cell returns to its resting state.

But funnel-web venom stops the ion channels from closing.

So the neuron unleashes a flood of neurotransmitters, like adrenaline, throughout the nervous system.

So muscles, normally under precise control, receive rapid chaotic signals causing them to tense up or spasm.

Which is a big problem for the heart, which begins to pump faster, raising blood pressure, and spreading the venom further around the body.

And eventually your body runs out of neurotransmitters.

Without them, nerve cells can no longer tell muscles what to do, so you're effectively paralyzed.

And it's only a matter of time before your heart or your lungs give out.

Humans are particularly unlucky, funnel-web venom is not that deadly to most mammals.

If something like your dog, or your cat, or a rabbit gets bitten by a male funnel-web spider even, even the male, they'll show very few symptoms.

And then you could also be bitten by the exact same spider, and be in a very severe way.

And that's because the effects of venom are very species specific.

Delta hexatoxin binds to a specific site of the sodium ion channels in primates, which causes chaos.

But that same spot isn't there in other mammals.

The lethality of this venom in humans seems to be an accident.

It only affects invertebrates, which are their prey and also primates.

So it's really toxic to monkeys, and apes, and of course, we are extremely badly affected by that.

The first people arrived on the continent around 70,000 years ago, but this spider evolved 40 million years ago.

And it just happens to be extremely deadly to people.

So it seems like an unfortunate coincidence that venom originally evolved for effectiveness against insects turns out to be deadly for us.

The people here at the Australian Reptile Park try to prevent that by making life-saving anti-venom.

But to produce it requires collecting venom from their stock of spiders.

We actually rely exclusively almost on public donations in order to keep the collection going.

All of these spiders would've been caught up by someone that has found it in their backyard, or in their swimming pool, or something like that.

You heard right, funnel-web spiders can actually survive underwater for up to 30 hours.

They do this by trapping tiny air bubbles in the hairs on their abdomen.

So if you see a funnel-web spider at the bottom of a swimming pool that doesn't necessarily mean that it's dead.

It's much more efficient for us to have spiders handed in that are already adults, they're moving around, they're mature males, and we can start milking them straight away, we haven't had to do any of the work to raise them.

And then, yeah, we'll milk them for that period of time.

Here's how you do it.

First, you poke it.

So that's kind of the funnel-web spider defensive stance, they'll raise in the air like that, and expose their fangs.

Sometimes they'll actually form drops of venom just on the tip of each fang.

Which is when we come in with a tiny vacuum.

You basically just use it as you would a pencil, and just stroke the tip of the fang with that.

Okay, I see that I got a little bit.

Sucked a big drop up.

Well, this is about as close as I ever want to get to a funnel web.

Say we milk about 50 spiders a day.

If you were saying each spider produced four to five drops, you know you're only talking about maybe 250 drops of venom.

What we've got in the end of the pipette there now would be enough to kill perhaps a dozen or so adult humans.

To get one vial of anti-venom, they have to milk 150 spiders by hand.

That takes 12 hours.

12 hours out.

It's a lot of work.

Milking a spider to save one person.

Exactly, yeah.

I mean I think that's worth it.

The venom is frozen, and sent down to a lab in Melbourne, and there rabbits are injected with it.

Now, although it's not as toxic to rabbits as it is to humans, they still start with a low dose, and then over a period of six months, they gradually increase the dose as the rabbits build up their immunity.

And once they can withstand six times the lethal dose, their blood is collected, and it gets spun on a centrifuge to separate out the antibodies.

And it is these rabbit antibodies that form the life-saving anti-venom.

Rabbits and people are similar enough that rabbit antibodies can still neutralize funnel-web venom inside our bodies.

Every year around 40 people get bitten by funnel-web spiders commonly from not checking their shoes in the morning.

And fortunately, due to this program, no one has died since 1981.

So for over 40 years now, we haven't seen a single death from one of these spiders.

Before we end today, I want to thank today's sponsor, BetterHelp.

BetterHelp's mission is to make therapy more accessible to more people, and I think that's a really important goal.

You know, finding a good therapist is hard, especially when you only have the options in your city.

And it can be even harder to find time in your schedule to travel in and meet them.

BetterHelp changes the game on all this, it's an online platform, it's remote.

And by filling out a few questions, you'll get matched to a professional therapist.

And if you don't really fit with that therapist, which is a common thing, you can easily switch to a new one for free without stressing about insurance, who's in your network, or anything like that.

Regardless of if you have a clinical mental health issue, like depression or anxiety, or if you're just a human being who lives in this world who has fears or stresses therapy can give you tools to approach your life in a very different way.

And it's easy to sign up, there's a link in the description which is betterhelp.com/veritasium.

Clicking on that link help support this channel, but it also gets you 10% off your first month at BetterHelp, so you can try it out, and see if it works for you.

So I wanna thank BetterHelp for sponsoring Veritasium and I want to thank you for watching.