The invasive Jorō spider has made headlines for its gigantic size; striking colors; and plentiful webs, which can stretch six feet long and are strong enough to support a bird’s weight.
“It’s a scary-looking spider that makes giant webs on your back porch,” says Andy Davis, a research scientist at the University of Georgia. “And it freaks people out.”
Originally from Asia, scientists believe Jorō spiders first came to North America in 2013 as stowaways aboard a shipping container. Since then, the spiders, which are harmless to humans, have quickly colonized Georgia and its bordering states, with Davis’ research suggesting the species could soon thrive across the eastern U.S.
But a new study, published this week in the journal Arthropoda, provides a bit of good news for the nation’s arachnophobes: After extensive laboratory testing, scientists conclude that the Jorō spider is actually a huge scaredy-cat.
To arrive at this conclusion, scientists collected dozens of Jorō spiders, golden silk spiders (related arachnids that are also non-native to the U.S.), marbled orb weavers, garden spiders, and banded garden spiders—the last three of which are native to North America. Then, they tested the arachnids’ responses to a “mild disturbance”—getting blasted by two quick puffs of air from a turkey baster.
On average, the native spiders froze for about 96 seconds after getting hit by the air. This freezing response is known as thanatosis, or death-feigning, and it’s thought to help the spiders hide from predators. But when it was the Jorō and golden silk spiders’ turn, the stopwatch ran for more than an hour before the animals started moving again. (Get a mesmerizing look at nature’s eight-legged wonders.)
“Everybody’s sort of had this impression that the spiders are rapidly expanding their range because they’re aggressively taking over and outcompeting all of the native spiders,” says Davis, who led the study.
Instead, the new research suggests Jorōs are the shyest arachnids on record. “It still blows my mind.”
Yet being timid may ultimately benefit the spiders, making them more cautious and less likely to get eaten or killed, he adds.
Setting the mood
When Davis and his co-author, undergraduate researcher Amitesh Anerao, tested the Jorōs’ and their close kin, the golden silk spiders, in the lab, they quickly became puzzled.
“We thought we were doing it wrong, because nothing happened,” recalls Davis. (Read how spiders may dream.)
As spider after spider started to require as much as two hours each to recover from the air blasting, the scientists had to think fast. After all, the building was closing for the day.
“Ultimately, I actually had to take all the spiders' home in tiny test tubes, set up little bins in my apartment to emulate the lab, and do the trials there,” says Anerao in an email.
“The only person with me was my girlfriend, so it was pretty easy to create a quiet environment, but having tubs of giant, palm-sized spiders definitely was not the most romantic decoration for my room.”
But Anerao was intrigued by their long freeze times. “It gave me the sense that we were on to something.”
Meek and mighty?
Jian Zhou, a postdoctoral researcher at Argonne National Laboratory in Illinois, who was not involved in the research, says “it’s quite shocking to learn about the hour-long startle responses.”
However, he also said the study raises many more questions.
“Yes, these spiders are the 'shyest' if the shyness is defined by the startle time,” says Zhou, who has studied other orb-weaving spiders. But “what is the behavioral significance of this long startle response in the spider’s life?”
For instance, Zhou wonders, “How would a startled spider respond when a juicy insect becomes trapped in its orb web?” (Learn more about the wonders of spiderwebs and silk.) [good link! Forgot about that one]
While Davis and Anerao had believed an aggressive nature propelled the Jorō’s spread, particularly in urban areas such as Atlanta, they’re now considering whether the opposite might be true.
Perhaps Jorōs and golden silk spiders prosper in highly stressful cities because they hunker down rather than run away from every noise, movement, or vibration.
Adding fuel to that hypothesis, researchers in Australia have shown that when another closely related arachnid, the tiger spider, inhabits urban areas, it grows larger and produces more offspring.
“It’s too much of a coincidence for three members of this genus to be highly urban-tolerant,” Davis says—suggesting their shyness may be a key factor.
Perhaps the meek shall inherit the Earth after all.