Ryan MacDonnell was volunteering in Limpopo Province, South Africa, when he came across two giant baboon spiders that were anything but itsy bitsy.
The Canadian wildlife biology student was surprised when the smaller of the tarantulas started drumming, or tapping its legs with increasing frequency. MacDonnell, an arachnid aficionado, recognized this as the male’s mating dance and quickly whipped out his camera. (Read "Bondage, Cannibalism, and Castration—Spiders’ Wild Sex Lives.")
“I was really excited,” he says. “We all knew it was something you never see in the wild because, to stumble across it, there’s maybe a five-minute window where a male happens to wander in.”
In the video, the male spider drums and shakes his body before the two approach each other, intertwining their legs for less than a minute while the male deposits his sperm into her genital opening before scampering off.
Sarah Crews, a biologist at the California Academy of Sciences who studies spider mating, said the video was unusual because these burrowing arachnids, found throughout Africa, are most often seen mating in captivity.
And it might have been just as rare to see both emerge with their lives: Many female Harpactira gigas will eat the male after sex, she says.
“Sometimes males try to mate with the wrong species because they don’t know and they’re just ready to go,” says Crews, who is also a National Geographic explorer. “Other times the male tries to mate with a female that’s not an adult yet, so she won’t know any different and might eat him.”
The female spider in MacDonnell’s video appeared to be almost twice the size of her suitor, which Crews said is typical of arachnids.
Females "keep the eggs, so they have to be bigger and healthier and stronger,” she says. “The male, he’s just going to go mate and then he’s going to go die.”
Female spiders also continue to shed their skin to grow throughout their lives, while male spiders stop shedding at adulthood.
Without a strong exoskeleton, the male tarantula protects himself females with spines on its front legs.
He first approaches a female with these legs in the air. “That’s because he’s using those spines to hold her fangs apart so they don’t stab him in the face,” says Crews. It could be worse for the giant baboon spider, though. A male widow spider will actually offer himself up to the female as a meal in the hopes that she won’t be hungry later to seek out another mate, Crews said. (Read how some male widows avoid becoming lunch.)
This increases the male spider’s chance of fatherhood—but at a steep cost.