Inside the Lab Where Spiders Put on Face Paint and Fake Eyelashes (and Termites Wear Capes)

March 20, 2019 0 By JohnValbyNation

In a lab at the University of Florida, researchers are giving male jumping spiders a makeover. After knocking them unconscious for a few minutes with carbon dioxide, the scientists paint the bright-red faces of Habronattus pyrrithrix black with liquid eyeliner, or stick false eyelashes to the heads of Maevia inclemens with Elmer’s glue. Welcome to Extreme Makeover: Arachnid Edition.

But … why? The jumping spider is already more of a showman than other species, known for its dance-heavy mating rituals—lots of emphasis on arm waving, à la one of those dancing inflatable men. By tweaking the males’ appearance, the Taylor Lab is helping tease apart the complexities of the jumping spiders' flirtation.

A male Habronattus pyrrithrix lives with the unenviable knowledge that he is both a potential mate and a potential meal. You see, female jumping spiders are incorrigible cannibals—if he doesn’t do something right, he could end up in her stomach. He would do well, then, to send the right signals.

So what might those signals be? Well, they're mixed: Habronattus pyrrithrix males have enchanting red faces, which happens to be a color that signals toxicity in prey. But an especially rosy complexion can also signal that a male is healthy. “If we give them a really good diet, their faces become brighter,” says Lisa Taylor, a behavioral ecologist who runs the lab. “That all suggests that females should be paying attention to color.”

To figure out whether they were noticing, the researchers presented female spiders with male suitors who were either bare-faced or painted over with black liquid eyeliner (Urban Decay, if you must know). The data is still trickling in, but Taylor is finding that female spiders are indeed less likely to attack males with red faces versus their face-painted peers.

This suggests a red face is a kind of double signal. Well-fed males are redder, which may be a sign of their fitness. But red also acts as a deterrent, tapping into a female’s aversion to a color that typically screams I’m toxic. “One is like, I have to tell you how good I am, and the other one is, OK, I'm going to do all these things so you don't eat me,” says UC Berkeley behavioral ecologist Damian Elias, who also studies jumping spiders.

Taylor’s lab is also working with Maevia inclemens, a species of jumping spider whose males wear little crowns, known as tufts. The bigger the male gets, the taller this tuft gets. “This might allow a male to clearly indicate how tall he is,” Taylor says. “It's kind of a signal that would be clear and easy for females to assess.”

These experiments are also still ongoing, but the researchers have been gluing false eyelashes to the tops of the males' heads. Not, like, a whole eyeful of lashes—that'd be bigger than the spider—but the individual clumps of synthetic lash sold by companies like Ardell, cut down to the right size with dissection scissors. “We know that bigger males have larger tufts, so that at least provides initial support for the idea that these tufts contain information for females,” says Taylor. “Whether or not females are paying attention to them, we're not sure yet.”

There are some males in this species, though, that skip the tufts and instead wave black-and-white-striped legs to get the female’s attention and to perhaps signal toxicity. To test the female’s reaction to black and white, the lab outfitted termites with tiny striped capes. “We know that females will look at the striped termites quicker, so it seems like the pattern of bold black-and-white stripes gets the female's attention,” says Taylor. “But you would think if something gets a female's attention, it would also elicit more attacks, and that doesn't happen.” In black-and-white-striped males, then, the patterning may work as an attention-grabbing device that stops short of garnering too much attention—i.e., cannibalism.

Now that researchers are getting a better sense of what male spiders are signaling to females, they want to know whether those signals are honest—if a red face or a big tuft are actually signs of genetic fitness. That, though, is easier asked than answered.

In order for a message to be "honest," the female has to be getting strong genes from the male—he can’t be faking. But to figure that out, “you have to do these large multigenerational experiments," says Elias. "For a lot of animals, like spiders, it's incredibly difficult to raise those amounts of animals to be able to show that.” You know, because of cannibalism.

You could imagine, though, that there would be strong pressure on females to tell honest from dishonest signals. “It's in a female's benefit to discriminate those kinds of lies,” says University of New South Wales evolutionary biologist Michael Kasumovic, who also studies jumping spiders. Females really, really want good genes from their mates. That might make it difficult for the dishonest strategy to survive over evolutionary time.

Which is not to say everything the male jumping spider does has to be honest. After all, he’s up to some seriously elaborate shenanigans. In addition to all the colorful visual dancing, he’s also vibrating to get her attention. (Trust me, you want to watch the video above until the finale.) Remember that the female is extremely picky, so he’s under a lot of pressure to win her affection. And maybe some of those shenanigans don’t map directly to primo genes.

“I like to think of it like strategies used in advertising,” says Taylor, “where some amount of the information you send has to be honest. You have to communicate what product you're selling. Certain things you have to be honest about, but then we all know that marketers can do subtle things to maybe push us one way or convince us to buy something we probably wouldn't have bought before.”

Maybe he’s born with it. Then again, maybe it’s Maybelline.