A former PE teacher has upstaged David Attenborough by filming a special moment in the secret sex lives of weedy seadragons.

It's believed to be the first time anyone has captured the moment when the female dragon transfers her eggs onto the male's tail.

It is during the process of the transfer that the eggs are fertilised.

Photographer and keen diver Pang Quong filmed the seadragons at Victoria's Mornington Peninsula. He'd seen the their courtship dance before but never witnessed this pivotal moment.

"The actual courtship was rather an anti-climax," he said.

"They swam together, put the bases of their tails together and then just slowly rose to the surface.

"The female releases a stream of eggs and then like a magician with cards, they magically transfer across to the male's tail and then they actually float up and make contact with the tail and bingo, they're there."

Mr Quong said he couldn't believe what he'd captured.

"I was really quite terrified that the camera wasn't actually working because there'd be nobody, nobody would believe what I'd just seen."

David Attenborough would be 'really thrilled'

Pang Quong has been filming weedy seadragons off Victoria's coast for years. ( ABC News )

Despite a decline in young people studying STEM subjects — science, technology, engineering and maths — there's been a rise in citizen scientists.

Marine biologist Stephen Swearer believes the work of these enthusiasts is invaluable in understanding species at risk of becoming endangered, like the weedy seadragon.

"This is a good example of how citizens can collect information. It can provide documentation of a phenomenon and that phenomenon in turn then can inform any sort of future scientific discovery," he said.

"We really need to harness as much information as we can to help inform management practices around a threatened or endangered species."

Fellow marine biologist Sheree Marris said she'd she'd be surprised if Sir David Attenborough's crew don't call Mr Quong about the footage.

"David Attenborough has actually put together a documentary based on different marine animals and one of them included the weedy seadragon which Pang was involved in," she said.

"So I'm sure he'll be really thrilled that we've learnt this new aspect of the seadragon biology. He'll be really excited."