The secret to the Joro Spider’s success may lie in its ability to stay calm

The invasive Jorogumo spider remains calm even when stressed

Stephanie Pappas

East Asian wigeon spiders, found in the eastern United States, are known for their penchant for building 3- to 10-foot-long webs in crowded suburban and urban areas, and now researchers have discovered that a physiological tendency toward balance may help the spider tolerate the hustle and bustle of urban life.

The yellow and black spider has a body length of over an inch and thin legs that can reach up to four inches.Trichonephila clavataThe intimidating-looking reptile is believed to have arrived in the US from East Asia in a shipping container about a decade ago and was first spotted in Georgia in 2014. It has since spread to other states, including North and South Carolina, Tennessee and Maryland, and its physiological characteristics and range suggest it may eventually make its way all the way to northern Canada.

The new study suggests that the spider’s calm demeanor may be what’s driving its dominance on the East Coast. Compared to other spider species, jollos maintain a steady, but elevated, heart rate even under stress, according to a new paper published in the journal Nature Communications on August 12. Physiological Entomology“They respond to the stress that they see every day,” says Andy Davis, a research scientist at the University of Georgia who led the study. “They’re just better able to handle that stress.”

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Because these spiders live in close proximity to humans and in groups (sometimes in communal nests, which are the equivalent of apartment buildings), Davis initially thought that Joros might simply not be stressed. To find out, he looked at the spider’s “heartbeat.” Spiders have a central blood vessel in their abdomen that works a lot like the human heart, pumping a blood-like fluid (hemolymph) around the body. When the spider feels fear, these vessels pump faster.

To get a baseline heart rate, Davis first tried attaching heart-rate sensors to spiders in the wild, but couldn’t get reliable readings. So he brought the spiders into the lab and built a frame for them to spin their webs and rest on. Once the animals had acclimated to their new environment, Davis aimed a horizontal microscope at the spiders’ abdomens and counted their visible heart rates while they rested.

The researchers used the same method to examine 22 orb-weaver spiders and 20 golden silk orb-weaver spiders.Trichonephila clavipesFor comparison, the researchers also studied 19 fan-tooth spiders (Orb spider) and 18 striped garden spiders (Orb spider), both of which are web-weaving spiders that prefer quiet environments.

Davis’s co-author, Christina Vu, then an undergraduate student, stressed the spiders by restraining them with pins between their legs and through their abdomens, preventing them from moving from one spot to the next, even though the spiders can wiggle. “This was amazing,” Vu says. While the orb-weavers and spiders were docile, the garden spiders put up a fierce fight. “There were a few times when we had to let some of them get away because they couldn’t move fast enough,” Vu says. (After the study was completed, all of the spiders were released back into the wild.)

Yet Vu and Davis found that the orb-weaver spiders were not immune to stress. When restrained, the spiders’ heart rates doubled, no different from those of the golden orb-weaver spiders (thrice the rate of the yellow orb-weaver spiders). All spiders’ heart rates remained elevated while restrained, never returning to a calm, resting rate. But the orb-weaver spiders’ and orb-weaver spiders’ heart rates showed less variability than the golden orb-weaver spiders’ over the course of the 10-minute experiment. That is, when their hearts were beating faster, their heart rates stayed high and steady, rather than spiking and plummeting as in the two orb-weaver spiders.

“Jorogumo spiders seem to be very calm overall,” Vu says. “They don’t try to fight back. They just accept things as they are. I think that’s why they get on so well with humans; they can handle a lot more because they don’t react as much.”

The findings complement a 2023 study by the Davis lab, which found that wigeon spiders freeze when exposed to wind stimulation for up to an hour, much longer than other spider species. In both cases of restraint and stimulation, wigeon spiders appear to be more inclined than other species to wait out the problem rather than fight or flee.

“Some spiders are more urban tolerant, and some are less urban tolerant, and uncovering physiological or behavioral differences could help us understand more about the biology of a species,” says Erin Grabarczyk, a biologist at Valdosta State University in Georgia who studies the biology of orb-weaver spiders but was not involved in the study. Studying differences within species would be interesting, she added, noting that the individual spiders in Davis’ study appeared to respond to stress differently.

Researchers need to study more species to confirm the link between physiology and lifestyle, Davis said, and he would also like to study solitary versus social spiders.

“If you’re a spider and you live in a world where it’s stressful every day or every hour, you can’t just run away every time a spider comes,” Davis says. “This might be a way of dealing with all that stress.”