"It doesn't work as well with the ladies as you'd expect," Zac Bower says, breaking into a laugh.

Zac, 27, is responsible for milking "about 250" of the world's deadliest snakes at the Australian Reptile Park on NSW's Central Coast as part of its vaccine program.

For 50 years the Reptile Park has been the only provider of terrestrial snake venom required for Australia's snake bite vaccine production, estimated to have saved 20,000 lives in that time.

What that means is that every day Zac has to handle - albeit very carefully - a who's who of reptilian nastiness ... coastal taipans, king browns, tiger snakes, death adders and eastern browns.

For the record, they rate second, third, fourth and fifth for world snake toxicity, with the king brown coming "about 12th to 14th".

"But the king brown is so big that it injects far more venom than the others," Zac says.

"And they don't like to let go. When they bite they hang on. You have to pull them off."

So much for the oft-repeated message to stay calm and don't move around if you're ever bitten. I admit I'm not a snake person, but show me someone who doesn't move much with a two-and-a-half metre king brown latched on to his leg and I'll show you someone who's already dead.

It begs the question: who exactly would want this job, where surely the biggest KPI is to stay alive?

Zac Bower, that's who - and he's wanted it from when he was knee high.

Zac grew up in a NSW Central Coast snake environment. He pulls out his phone and show me an old picture of his dad Mac - sporting a mullet that would win prizes at Mulletfest - holding a fully grown python. There, beside Mac, is young Zac, maybe three years old, brandishing a smile almost as big as the python, not a care in the world.

"Dad always had pythons, so I grew up around snakes. Having said that my stepmum was catatonically afraid of snakes, but that's another story," he says, grinning at the memory.

"I did work experience here at the Park when I was 16, and then kept pestering them until I was 18 and old enough for them to hire me."

A short time later he was moved into his dream job, working with venomous snakes.

We're just entering the snake milking area - essentially Zac's office - when he turns to the photographer Simone and me and says: "Please don't open any of the enclosures."

Seriously?

"I know," he says almost apologetically, "but I have to say it."

The venomous snake area takes up three adjoining rooms, all lined with snake enclosures.

"We milk our snakes every three weeks and never feed them before milking. That way we get more toxin. The snakes will naturally keep some venom back for food. But seriously, most of my week is spent cleaning out the enclosures."

That means transferring the snakes into wheelie bins while the cleaning takes place. So, as an invited guest, lifting the lid on a wheelie bin is another serious no-no.

Most of the snakes are male as they tend to be bigger and can produce more venom. In the case of death adders, it's the other way around, so there are more females.

It's obvious that there's a sticker system in play, because a handful of the enclosures have red or yellow stickers, some with both.

The yellow stickers come with the self-explanatory note of Caution, High Caution, or Extreme Caution.

Some have more than one yellow sticker.

"Whitey over there," Zac says pointing to a nearby enclosure, "he's a coastal taipan and he's had so many stickers they started falling off. He's our worst. You've got to be super careful with him."

The red stickers come with names. Whitey has one for starters. Then there's Leroy - "as in Bad, Bad Leroy Brown" - Ninja, Base Jumper, Nervous Ned, Speedy, Stock Whip and Cyclone, among others.

If this was a prison, these are the maximum security guys.

"Okay, give me an example," I say. "What makes Stock Whip so dangerous?"

"He does these big, circular swings of his body when I hold him, trying to get closer to me, and then he launches out."

And Ninja?

"Just a cool name. He's an eastern brown with a real tendency to bite."

IN OTHER NEWS:

If Zac's apparent calmness seems a touch gung-ho amongst all this reptilian menace, don't be fooled.

"My hands are shaking after I've finished milking them," he says.

"The day they don't shake is the day I give it away because I'm getting too comfortable and that's dangerous."

Even now, with eight years' experience behind him, there are days when he refuses to milk.

"Some days I'm just not feeling it," he says. "I'll come back and milk the next day. It's just not worth the risk."

It raises the question about whether Zac has ever been bitten.

"At the Park we don't like to talk about it," he says.

"But we prepare for it and we practice it.

"If someone gets bitten we can get them bandaged up and to Gosford Hospital inside 18 minutes, and that's pretty good."

While not all the snakes have names, Zac knows them all individually.

I pick an enclosure at random. Who's that snake, I ask?

"He's a coastal taipan, who's getting on in years," Zac says.

"He's pretty calm compared to, say, the one in the enclosure below him. He's younger and a bit jumpier."

It's clear that Zac loves his snakes. And they know him and clearly feel comfortable with him, although they have different ways of showing it. Ask Whitey.

"People have to understand that snakes want to keep their venom for killing prey so they can eat," Zac explains.

"They just want to be left alone. The last thing they want to do is bite something they can't eat.

"And think about it: everything hates snakes. Cattle and horses, birds, frogs and lizards, dogs and cats ... there's nothing out there that likes snakes.

"Life's pretty tough for them. They just want to be left alone.

"They get in these threatening poses to scare you off, so they won't have to bite. The cobra with its flared neck and the rattlesnake with its tail rattle, they're probably the most obvious examples of that."

I've been sitting listening to Zac when I notice movement in one of the small plastic containers about 30 centimetres from my head.

"Baby tiger snakes, our next generation," Zac says. "Ten of them."

And then it's time for a snake milking demonstration.

Zac goes to Nervous Ned's pen and brings him out ... a big, brown taipan probably two metres in length.

"Don't worry," Zac assures us. "He was worse a few years ago. He's more relaxed these days."

Which, it needs to be said, hardly makes him Bambi. But Zac confidently grabs him by the tail, holding him at arm's length, twisting his body to keep his head away.

He gently manoeuvres Ned - see, we're on first name basis already - until his head is low to the ground, hovering just above a firm foam cushion at Zac's feet. Then he moves quickly, using a plastic pinning disc - think of it as an oversized potato masher - to pin Ned's head on the cushion.

Then Zac slides his hand under to grab Ned from behind by the head and neck. At that point his relief is palpable.

He lifts Ned up and is happy to pose for the camera.

"It's important to know that the foam cushion means we can't hurt the snake when we pin him. Milking is painless for the snake."

He brings a plastic cup to Ned's mouth and he happily does what taipans do. The venom, almost clear but with a very pale pinkish tinge, starts to run into the cup. Job done.

After the not insignificant challenge of returning Ned to his pen - he seems to like this freedom caper - Zac shuts the door with death adder speed.

Next up, it's Leroy - as in 'Bad, Bad Leroy" ...

He's paler than Ned - presumably a blonde - and more restless. Zac is particularly careful, and needs to wag his finger to attract his attention and get him to bite, which he soon does with some enthusiasm.

"I've got another one I want to show you," Zac says. "It's Angus, he's our biggest snake, but he's not ready for milking."

Angus is a monster king brown, all 2.6 metres of him.

"He weighs 18 kilos," Zac says. "When these guys hit the milking cup they strike really hard."

Even for Zac and his front rower's build, handling big Angus is a real handful.

"Look," he says when Angus is back in his enclosure, and he raises his hands. As usual, they are shaking.

So, are there any of his snake family that are a dream to handle?

Say hello to Barry, clearly a Zac favourite. He walks into the next room and brings out a death adder.

"This is Barry and he's the coolest, calmest death adder you'll ever meet."

It's apparent that Barry is about as far removed from Whitey as it's possible to get.

Zac scratches Barry's back down near the tail.

"Normally that would trigger a strike, but not with this guy," Zac says. "He's just so calm."

The Reptile Park selectively breeds to increase venom production - the more venom they can supply, the more vaccine comes out the other end.

In broad terms it means matching a male who produces loads of venom to a female with loads of venom and then let snake romance do its things.

"In the wild, for example, a coastal taipan produces 0.9 grams of venom per bite. Here our coastal taipans are producing 2.2 grams per bite. And Nervous Ned actually produced 4.9 grams one bite. That's five times the normal amount."

After milking the venom is placed into what, for all intents and purposes, is a fancy fridge where the venom is dehydrated into a pure venom powder.

At that stage, it can be sent to bioCSL in Melbourne where it is rehydrated and used to produce vaccine.

It should be noted that one milking does not produce enough for a vaccine dose. It takes closer to 20 milkings to produce enough venom for a dose of vaccine.

And in many cases it takes multiple doses of vaccine to overcome a bite. So it might take Zac more than 100 milkings to save one life.

Yet statistics show how overwhelmingly successful Australia's vaccine program has been.

Despite universal acknowledgement that Australia has the world's most poisonous snakes, we only average about two deaths per year from snake bite nationally. Globally there are between 80,000 and 120,000 snake bite deaths per year.

And while Zac clearly loves his job and the important role he plays, he knows he has a shelf life.

"I'm actually in the process of training up an apprentice now," he says.

"He's been with me about 12 months now, but obviously it's not a job you can hurry.

"He's at the stage of handling snakes but not milking them.

"When he's ready we'll start him off milking a few of the hand-picked, fairly relaxed red-bellied blacks and the like, and he can work his way up."

Of course, handing over the reins will mean handing over the sexy job title as well.

"I know, it will be a sad day," Zac says, again breaking into that familiar laugh.

Time for one last question.

The Park milks poisonous spiders too, are you involved in that, Zac?

"You're kidding me. No way, spiders give me the heebie-jeebies."

Go figure.

It seems a simple enough question, yet no two lists are exactly the same. Why is that?

"Well, the deadliest snake and the most toxic snake aren't the same thing," Zac explains.

"The deadliest snake is the one that kills the most people. That would probably be the Russell's viper, which lives in India and south-east Asia and is responsible for something like 40,000 deaths per year.

"But in those countries a lot of people go around bare-footed, vaccine is often not available or not nearby, so the death count is high.

"In Australia we only have between one and three deaths a year on average."

By comparison, the most toxic snake is the inland taipan, also known as the fierce snake. But it lives in the searing heat of remote central Australia where the population is very low, as is the number of fatalities.

"It's so venomous that we don't milk it here at the park," Zac says.

Then there are other variables. The king brown isn't right at the top of the toxicity charts, but it injects more venom than other snakes.

"It's not as straight forward a question as you would think," Zac adds.

Snake toxicity is measured using the LD50 scale. LD (Lethal Dose) 50 measures the dose required to kill 50 per cent of a tested population - usually rodents.