Tom Crutchfield, the reptile breeder and wrangler who supplied the creatures for the first two Indy films, said most of the cobras in the famous "Why did it have to be snakes?" sequence were European legless lizards.

"We got hundreds and hundreds of these, and we put them in the refrigerator down to 35 degrees Fahrenheit [1.6 Celsius]," the 65-year-old American said.

"When you take an animal that's ectothermic, cold-blooded, and you get it cold, it can't move around much, it doesn't want to move around much, and it's not harmful at all to these lizards."

Crutchfield admitted there were cobras moving around the lizards, but the one that hisses at Harrison Ford was behind a piece of glass, with the snake handler just offscreen.

"But that's how they could film that scene...there's no possible way you could've duplicated that without the lizards."

Crutchfield is a special guest at this Saturday's Scales & Tails Expo at the RNA showgrounds, a mecca for Queensland's expanding community of herpetophiles.

Owner of Scales & Tails magazine Steve Castell said their seventh annual expo had to move to Brisbane because it had outgrown its previous home Ipswich.

"There are over 135,000 licenced reptile keepers in southeast Queensland and close to half a million in Australia, it's a massive market," he said.

"And it's only just taking hold here...there are 50 million reptile keepers in the United States, and the bearded dragon is the second most common household pet in the UK, after dogs."

Bearded dragons?

It's true, Mr Castell said, outlining how thousands of the lizards and their eggs were taken out of Australia in the 70s and 80s before export laws were tightened.

Mr Crutchfield cited the bearded dragon's cleanliness, independence and suitability for smaller spaces like apartments as key benefits.

"The dog has to have companionship, the reptile does not," he said.

"For people who have jobs that take them away from home it makes a perfect pet, whereas a dog would suffer."

Scales & Tails' other special guest is Kenan Harkin, a former professional BMX trick rider and announcer whose Animal Bytes YouTube channel has nearly 250,000 subscribers.

His Kamp Kenan series is based around his Florida sanctuary, where he promotes conservation and breeds reptiles such as his favourites, turtles and tortoises.

"It can be hard to see the humanity in a reptile, there's no muscle in their face, they don't smile or anything like that," he said.

"But I think the fascination is looking into the past, into pre-history...every human has a reptile brain."

Mr Harkin said the enduring popularity of dinosaurs proved children don't start life afraid of reptiles, but inherited irrational fears from their parents.

"I got into reptiles because of Godzilla movies when I was five...I was lucky that I had a mother who helped me learn more about them and let me decide how I wanted to interact with them."

"We want people who are shit-scared of snakes to come to this exhibition, that's our target market," Mr Castell said.

"You may not love them when you come out, but at least you'll know more about them," Mr Harkin said.

"And knowledge is the only difference between scary and wonder," Mr Crutchfield added.

All three are passionate about conservation, saying captive reptiles are an important part of an "invisible ark", which could help repopulate areas where  wild animals go extinct.

"They were here before us and there'll be here after we're gone," Mr Crutchfield said.

"Humans are at top of the food chain, which means we have to be stewards of the planet and ensure we understand and protect all animals, not just the cuddly ones."

The Scales & Tails Expo runs from 10am on Saturday November 1 at the RNA showgrounds, with tickets $10/$5.

*Correction: An earlier version of this story listed the Indiana Jones scene as being from The Temple of Doom. The author apologises for this shocking pop culture oversight.