A giant huntsman spider photographed by a Queensland animal rescuer last year is "quite normal in size" and only looks really big because of its "unusual perspective", an arachnologist says.

Someone from Barnyard Betty's Rescue rescued the "amazing creature" from being killed last year, according to a Facebook post which this week went viral online.

"The tree and the broom are in focus so you're getting this unusual perspective," Dr Robert Raven, who is Queensland Museum's principal curator (Arachnida) and head of terrestrial environments, said.

"It's quite a normal size of this species — and I've got a live one on my desk at the moment — the placement of the tree behind it makes it look like it is as big as the tree."

The female spider pictured in the photograph — who was christened Charlotte — was released back onto the farm last year.

Charlotte was described as a "beautiful, calm spider" and "not aggressive in any way".

"Like most spiders she just wanted to go about her business eating bugs and living in peace," the rescue organisation wrote on Facebook.

Will Charlotte get any bigger?

Charlotte the spider was described by the person who found her as "the best rescue yet". ( Facebook: Barnyard Betty's Rescue )

Huntsman spiders are known for being large and long-legged, with the species of the one pictured growing to an approximately 15-centimetre leg span and higher.

"The biggest huntsman in the world by leg span is a south-east Asian one, [which has] a 30 centimetre leg span," he said.

"We've got species of that genus in Australia and the ones in North Queensland get up in size — not to 30cm — but they get big, big spiders there.

"The one pictured is one of biggest species in North Queensland."

Dr Raven said the spider appeared to be an adult, so it would be unlikely to get any bigger in leg span.

"The only thing that will change of any substance is that the size of the body [the abdomen] itself will probably get bigger," he said.

Where do huntsmen like to hide?

Last month, a central Queensland tradie filmed a huntsman spider clutching onto a small mouse and trying to drag it to the top of a fridge.

Dr Raven said this is the time you should expect to see more huntsman and bigger spiders out, as the dry weather forces the spiders to seek out somewhere moist to lay their eggs.

"Huntsman spiders usually only come out at night and they like quite dark, tight spaces. So one of the best places to find a huntsman is behind a towel and a wall in the bathroom," he said.

"It's a close area and the towel would probably be a bit damp and they need to find places that are a bit moist because they need to lay their eggs in moisture.

"What they'll do is they'll lay their eggs in the bath towel and when you go to run the bath, as what happened to one lady, hundreds of baby huntsman came swarming up the walls of the bath."