Rare dual-coloured funnel-web spider

  • August 13, 2015

A genetic mutation has caused a rare colourful funnel-web spider

Contributor
Becky Crew

Becky Crew is a Sydney-based science communicator with a love for weird and wonderful animals. From strange behaviours and special adaptations to newly discovered species and the researchers who find them, her topics celebrate how alien yet relatable so many of the creatures that live amongst us can be.

This is one of the most unique spiders you'll probably ever see. Found in the Tallaganda State Forest of NSW, this is a member of the elusive Atrax sutherlandi species of Australian funnel-webs, a close cousin of the notorious Sydney funnel-web (Atrax robustus).

If, like me, you're utterly charmed by this little beauty, I've got some good news and some bad news for you. The bad news is that A. sutherlandi doesn't usually look like this. It looks like this, with an incredible glossy black pigment all over, and not a hint of that gorgeous orange and red.

The good news? Thanks to the scientists who found the specimen in the picture above, you get to appreciate the results of a very rare genetic mutation that's allowed these colours to be expressed.

Mark Wong, an invertebrate zoologist from the Australian National University (ANU), says he and his colleagues were on a routine collecting trip, surveying the forest floor for the distinctive shelters strung together by funnel-web species. Having stumbled on an extensive web network, he started poking it with a twig, until something large - about 5cm long - sprung into action.

"Before I knew it, boom! She had rushed out of her silken lair with her legs raised and fangs greeting me with glistening venom," says Mark. "Instantly taken aback by her colours, I knew there and then, this was something special."

funnel-web spider
A funnel-web spider with a rare red colouring. Credit: Mark Wong

Red pigment normal for funnel-web spiders

Mark says the red pigment seen on this pretty lady has been found elsewhere in both the A. sutherlandi and Sydney funnel-web species - such as on their undersides or across their fangs and mouth parts - which means they clearly have the genes to produce the red pigment.

"So what we are seeing in this particular specimen may be a case where the genes for red pigment are being expressed in the wrong tissue," he says.

"Alternatively, it is possible that 'normal' funnel-web spiders do actually express red pigment in the areas that show up clearly in this 'special' specimen, but it's just that the red is usually obscured by brown or black melanin in the 'normal' spiders," he adds. "Perhaps in this specimen, the melanin genes have not been expressed, thus revealing the red pigmentation underneath."

Mark says despite looking specifically for more A. sutherlandi species with similar colour patterns, he and his colleagues have so far turned up nothing. If they did, it would be an incredible help to them in figuring out how this specimen came to be, and what genetic or perhaps environmental factors were at play in forming it.

For now, this red lady can be comforted in the knowledge that as of the scientific record, she is entirely unique.

A love affair with funnel-web spiders

Mark, who confesses a life-long fondness for "things with many legs", says he was fascinated by the distinctive beauty of the funnel-web spiders from the moment he was introduced to one by ANU's resident spider expert, Dave Rowell. "I was captivated by how its glossy, dark integument reflected the sunlight, and simply amazed when Dave said it was likely well over 20 years old!"

As someone who's collected hundreds of funnel-webs with his colleagues over the years, Mark has had time to perfect his spider-catching technique. Do not try at home, obviously:

"We first look under rocks and fallen logs for the entrances of their subterranean burrows, which are often skirted by a silken funnel-shaped web. Upon discovering a burrow, we determine its depth and direction using a probe, then gently scrape away the earth accordingly till the creature is revealed... The spider is then carefully transferred to a container with the aid of gloves and long forceps. As the spiders are usually hiding deep underground (>25cm), there's really no easy way to collect them and it usually takes between 10 and 30 minutes just to retrieve one specimen."

See below for what that looked like when he met the dual-coloured Atrax sutherlandi: