Spider Butt

Some spider abdomens look like predators. This is used to evade predators. 

A University of Cincinnati student is researching how spider abdomens appear to mimic the appearance of their natural predators in order to attract a mate.

Doctoral student Olivia Harris studies visual ecology and perceptual realities – or how organisms use what they see in constructing how they perceive their environment, as part of this research, Harris noticed that the backs of male peacock spiders mimic the appearance of other predators like wasps.

“Humans are excellent at seeing faces where there aren’t faces,” said Harris, adding that the real question is whether other spiders will notice this similarity as well.

Programing artificial intelligence (AI) software to accurately identify the structural features of different predator’s faces, Harris – who spent her time as an undergraduate studying marine invertebrate species – found that the spider abdomens were able to fool the computer in 5% of identifications.

Although 5% does not seem like a very significant figure, the AI was programed to be as accurate in identifying organisms as possible to make each misidentification even more significant, she said.

As female spiders are known for being cannibalistic, males need a competitive edge to be safely noticed in mating, said Harris. She believes male spiders developed this adaptation to give them just that.

“When jumping spiders are scared their instinct isn’t to run like other things, they actually freeze,” she said. “If [the male] can startle [the female] a little, he can kind of capture and maintain her attention while keeping himself safe.”

The next step is to blur these images in such a way that will simulate a spider’s vision and feed those images back into the software in hopes of getting different results, she said.

Already this approach has had promising results, with a 3% decrease in identification accuracy, said Harris.

This research is unique because while most organisms imitate prey in attracting a mate, this spider is doing the opposite, she said.

“We have never found another case where the male actually wants to look scary in order to flirt better with the female,” Harris said. “Fear and flirtation almost never come together in the animal kingdom.”

Earlier this month, Harris presented these findings at a conference of Society of Integrative and Comparative Biology, where she says there has been a positive response from others in the field.

Although the research is ready to be prepared for publication, she would like to add a behavioral component to compliment the machine-learning research.

Because the peacock spider is native to Australia and the bushfires still raging across the southern half of the continent, obtaining a collection of specimens for research is not anywhere on the horizon, she said.