How scientists found 'Nemo,' Australia's newest dancing spider

In a wetland near South Australia’s Mount Gambier, Sheryl Holliday crouched in ankle-deep water, camera lens trained on blooming purple orchids a few feet away. Just as Holliday prepared to hit the shutter, she caught a glimpse of something tiny jumping out of the frame. 

She didn’t know it on that clear day in November, but she’d just discovered an entirely new species of peacock spider, a group of little-known Australian jumping spiders known for vibrant colors and elaborate mating dances.

“I’ve been chasing peacock spiders for three or four years,” says Holliday, an ecological field officer for Nature Glenelg Trust and citizen scientist, but this one looked different. For one, its abdomen was drab, and the creature had distinctive orange-and-white facial patterns. (Read how male peacock spiders use optical illusions to woo mates.)

Intrigued, Sheryl shared her photos to a Facebook peacock spider appreciation page, which caught the attention of page administrator and arachnologist, Joseph Schubert, who had never seen one like it before. 

The pair connected, and Holliday collected and sent live specimens to Melbourne, allowing Schubert and colleagues to formally identify the arachnid as Maratus nemo, after Nemo, Disney’s heroic clownfish. (The Walt Disney Company is majority owner of National Geographic Partners.)

The Nemo peacock spider, described recently in the journal Evolutionary Systematics, is the latest in a flurry of peacock spider discoveries that has brought their known numbers from just 15 in 2011 to 92 today. (See more pictures and videos of newly discovered peacock spiders.)

Schubert, a biologist at Museums Victoria, credits the boom to the ease of modern photography, in which anyone can quickly take a photo on their smartphone and upload their findings to social media.

Of course, being popular also helps. These rice grain-size arachnids’ charming mating dance has led to countless viral memes that have made the peacock spider an internet sensation.

Movers and shakers

That doesn’t mean they’re easy to find. Most of the year, peacock spiders are brown; only males gain their striking colors after they molt in the spring. Combine that with their diminutive size, and it’s no surprise studying the non-venomous arachnids can be a challenge.

That’s why, when identifying a new species, Schubert hones in on the male’s colorations as well as their mating dance, which is unique to each species and involves a male flexing and gyrating to show off its fitness. When Schubert encouraged a male Nemo to dance for a female in the lab, he was surprised by what he found.

This one individual didn’t “lift its abdomen completely like other species, and it doesn’t have those opisthosoma flaps”—which give the spider its famous colorful display—"underneath the abdomen. It’s just got a little brown booty,” explains Schubert. (Read how peacock spiders get such blue abdomens.)

Instead, the male impressed the female by raising its third set of legs and vibrating its abdomen on the ground, generating an audible sound. It’s unknown, he says, whether this is a trademark dance of the Nemo peacock spider.

Schubert noted Nemo’s wetland home is also “really strange,” as the majority of other known peacock spiders prefer dry scrublands.

But peacock spiders are always surprising him. In 2020, scientists found one species, Maratus volpei, living in a salt lake. “We’ve learned that we should be more open to the sorts of habitats where we look for peacock spiders,” Schubert says.

Though peacock spiders play a valuable function as a predator controlling insect populations, there’s still far too little known about their role in the ecosystem and conservation status, he adds.

A tangled web 

“Peacock spiders are excellent because they challenge the prevailing view of spiders as being big, hairy, and dangerous,” says Michael Rix, principal curator of arachnology and research fellow at Australia’s Queensland Museum, who was not involved in Schubert’s study.

“This is a really excellent example of just how interesting, diverse, and still understudied the Australian spider fauna is,” Rix says. (See pictures of peacock spiders nicknamed Sparklemuffin and Skeletorus.)

Only around 30 percent of Australia’s invertebrates have been formally documented, and there could be as many as 15,000 spider species still to be identified.

Discovering new spiders can also benefit humankind, whether it’s controlling agricultural pests or inspiring new medical treatments, Rix says. Proteins from funnel-web spider venom are already being used to develop pain relief medication, as well as treatments for epilepsy, stroke, and potentially some cancers.

Meanwhile, arachnid and insect populations are plummeting worldwide. In Australia, habitat loss, wildfires, and pesticides may kill off entire spider species before we’ve had a chance to find them, Rix cautions.

“Fundamentally, we can't conserve our biodiversity for future generations,” he says, “if we don't know it even exists.”