For Jumping Spiders, Choosing the Wrong Mate Turns Deadly
Male jumping spiders are not what you’d call picky. In fact, the tiny arachnids try to court every female they see—even when she's a different species.
But boldness has its costs. Female jumping spiders are larger than the males, and voracious predators to boot. This means that every time an eight-eyed Romeo tries to woo a mate, he risks becoming Juliet's lunch.
Which is why it's more than a little odd that males would risk everything to court a female of a different species. (The males don't actually end up mating with these foreign females.)
The confusion isn't entirely the males' fault, says Lisa Taylor, an arachnologist at the University of Florida and leader of a new study about misdirected courtship in jumping spiders. (See "Jumping Spiders Can Think Ahead, Plan Detours.")
There are more than 5,000 jumping spider species worldwide, and many of them have overlapping habitats. And while males of different species can be distinguished by facial stripes and flamboyant colors, the females are less colorful and thus harder to pick out of a lineup.
“To waste such energy and to take such risks with females of the wrong species [with whom they have no chance of mating] seems like a bad idea,” Taylor says in an email.
“However, we suspect they do this because they can’t actually tell the females apart.” (See 10 beautiful photos that will make you love spiders.)
Violent Delights, Violent Ends
Mistakenly trying to mate with another species, or misdirected courtship, is common across the animal kingdom—lizards, fish, flies, moths, and many other creatures do it. For most of these males, the costs are much lower: "There is no chance that an unimpressed female will eat them,” Taylor says. (See "Monkey Tries to Mate With Deer in First Ever Video.")
To get a better understanding of the jumping spider dating scene, Taylor and her fellow researchers observed four species of jumping spider native to Arizona’s cottonwood and desert willow forests. This meant following individual spiders across the leaf litter and noting their every move.
When it comes to finding a partner, jumping spiders can rival any online dating stories you may have heard. Their courtship rituals are filled with deception, cannibalism and dancing. And in this micro-universe, the ladies call the shots.
After several months of spider-watching, Taylor created a diagram to tease apart the interactions between males and females of each species. The result, ironically, resembles a tangled web.
The scientists found that courtship occurred in 100 percent of interactions between males and females, regardless of the species.
When a male jumping spider encounters a female—literally any female—he launches into an elaborate courtship dance, including rhythmic flailing of limbs and complex vibrations. (Read "Bondage, Cannibalism, and Castration—Spiders' Wild Sex Lives.")
Sometimes these courtships resulted in the females attacking the males, and sometimes these attacks turned into successful courtships. Once, a female spider repeatedly attacked a male of her same species, but he kept after her, and the two eventually mated. Another time, a male tried the same tactic with a female of a different species and was devoured.
The scientists didn't observe enough courtship encounters to show that females of other species are more likely to eat courting males, but it did reinforce that males encounter substantial risks.
“I suspect that in some dense populations, males do make up a significant portion of female diets,” says Taylor, whose study was published recently in the journal PLOS ONE.
Erin Brandt, a spider biologist at the University of California, Berkeley, said the study supports what she’s seen from these creatures in the lab.
“In my work, we frequently use dead female ‘lures’ to entice males to court. Often, the species of the ‘lure’ doesn't matter,” says Brandt. “I have even seen especially enthusiastic males court dead females that have curled up and flipped over.”
A Midsummer Night’s Scream
“The male’s goal is to spread his seed around as much as possible,” says Faust. “If he gets eaten after successfully spreading his genes, well, so be it apparently.”
Of course, for the jumping spiders, that strategy would only work if the male sealed the deal before becoming the meal, and in Taylor’s study at least, mating and predation seem to be more of the either/or variety.
Still, Faust called the jumping spider research interesting, especially if it might lead to insights about the “very confusing and messy” business of how new species arise.
“Everyone is constantly evolving,” says Faust.