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Some jumping spiders look so much like wasps that scientists named them for the predatory insects.

But University of Cincinnati biologists wondered: Do these mimics really look like insect faces or is it just our own perceptual bias? After all, we see faces everywhere: tree trunks, rock outcrops, clouds.

So when travel restrictions from COVID-19 shut down field research, UC biologists decided to turn to an objective third party, a computer.

They presented digital portraits of jumping spiders, praying mantises and wasps to see if a computer algorithm could identify them correctly from shapes and patterns each contained. And surprisingly even the computer was fooled about 20% of the time.

The study was published in the journal Behavioral Ecology .

“The original idea was inspired by one species, a peacock jumping spider called Maratus vespa, which is Latin for wasp,” UC student and study lead author Olivia Harris said.

This jumping spider lifts its abdomen during an elaborate courtship display to reveal a colorful wasp-shaped back. The illusion is made all the more realistic by raising flaps on its sides that give the spider the familiar guitar-pick shape of a wasp’s face.

Researcher Jurgen Otto discovered, described and photographed the species in Western Australia in 2015 with co-author David Knowles.

“That got us thinking,” Harris said. “Why would a spider want to look like a wasp, which is a predator of spiders, especially as a primary element of its courtship display?”

It turns out that when spiders see distant insect predators, they tend to freeze in place and give their undivided attention to the potential threat. And that attention could give male jumping spiders the opportunity they need to begin courting the female

Researchers used computer vision techniques and machine learning and neural network algorithms to see if artificial intelligence properly classifies images properly as spiders,wasps, praying mantises or flies. The AI got it wrong across all 62 species nearly 12% of the time. And it correctly identified 13 species every time.

But the AI misidentified Maratus vespa and several other spiders more than 20% of the time and typically as wasps. Researchers said the next step would be to test their hypotheses with behavioral experiments with live female jumping spiders.

Deception is not unheard of in animal courtship. Some male moths simulate the sounds of echolocating bats to discourage potential mates from taking flight. And antelopes called topi have been documented warning does of phantom predators to discourage them from fleeing their territories.

“But this is the only case we’ve found of males mimicking a predator visually,” she said.

UC Associate Professor Nathan Morehouse, a study co-author, said the spiders appear to be using sensory exploitation to their advantage.

Morehouse said they found that the predator illusion works best at greater distances or in the female spider’s periphery, where she relies on eyes that see only in monochrome green. But once the male gets closer, the female’s front-facing, color-discerning eyes take over.

“Females will not be fooled forever. If they were, they would be robbed of the ability to make mate choices, which would put the species at a long-term disadvantage,” Morehouse said. “It’s beneficial for the males to break the illusion.”

In 1825 Michael Faraday isolated a sweet-smelling chemical that he dubbed bi-carburet of hydrogen. That molecule, better known as benzene, is perhaps the most famous molecular ring in chemistry.

Back in 2019, for example, a team led by Simon Aldridge at the University of Oxford made an aluminum complex that inserts itself into benzene, priming it for a reaction with a tin reagent that breaks open the ring. In addition, certain enzymes can pry open the benzene ring in catechol.

The team behind the new study instead drew inspiration from the kinds of metal complexes that can break the strong bonds in dinitrogen or carbon monoxide. First they made a scandium complex containing a pincer-like ligand that stabilizes a range of metal oxidation states. Then they mixed the complex with potassium graphite (KC₈), which is a strong reducing agent, and benzene at room temperature. This formed an inverted sandwich complex in which each of benzene’s faces binds to a scandium complex. In this arrangement, the benzene carries four extra electrons in its antibonding orbitals.

While exploring the chemistry of this sandwich complex, the team found that it reacted with metal carbonyls, such as chromium hexacarbonyl, also at room temperature. Theoretical studies led by team member Xiaotai Wang of Xi’an Jiaotong-Liverpool University suggest that this involves a series of carbonyl-insertion reactions that ultimately help to lengthen and then break one of benzene’s carbon-carbon bonds.

The product is a complex containing both scandium and chromium and with a linear hexadiene unit at its heart. “We discovered this reaction by chance,” Chu says. “But after we got the crystal structure of the product, we found that it’s very beautiful.” Adding carbon monoxide gas helps the reaction along, offering yields of up to 88%, and the process works just as well with toluene.

“Scandium is always good for a surprise because it’s one of the smallest, highest-charged metal cations,” says Sjoerd Harder of FriedrichAlexander University Erlangen-Nuremberg, an organometallic chemist who uses main-group metal complexes to activate strong bonds. Harder was not involved in the new work. “It can do stuff that other metals can’t do.”

Although many different metals have previously been used to create inverted sandwich complexes of benzene, Harder doesn’t think that anyone has tried reacting them with metal carbonyls before. “It could be that the other complexes react like that, but we just don’t know it,” he says.

Chu’s team is now trying to free the organic component of the product from its metal partners and—given the relatively high cost of scandium—investigating whether other metals could act as catalysts to achieve the same ring-breaking feat. “If he’s able to do this catalytically, then we’re talking,” says Harder.