In its native home, Japan, the Joro spider is known as a deceptive shape-shifter, whereas in Korea, it's considered a fortune-teller. But in the United States, the arachnid is gaining fame for being the latest invasive species to take over the country.
The Joro spider first arrived in the state of Georgia in 2013, and has since spread across the state and southeast. Scientists speculate the species may have taken up space in Georgia for a couple of possible reasons. For starters, its webs tend to hang at higher altitudes, where there is less competition with other spiders, who mostly tend to stay closer to the ground. On top of that, there has been a decrease in the numbers of the native species of the region due to pollution and loss of habitat, which is making more room for non-native species to thrive.
As the unstoppable species spreads across the country, ecologist Andrew Davis and graduate student Benjamin Frick of the University of Georgia conducted an experiment to find out how to stop the spider from expanding its territory to the north. They decided to test whether the species could tolerate the freezing climate of the north. The two researchers collected 35 wild female Joro spiders and 22 wild female golden silk spiders for the study. One way for spiders to keep their bodies warm in cold climates is to increase their resting metabolism. To test the resting metabolism of the spiders, the researchers placed the subjects in small, sealed containers and measured how quickly oxygen levels dropped in the container. Results showed the Joro spiders scored twice as high as the golden silk spiders, meaning they could better withstand freezing temperatures. The team then placed a separate group of spiders, consisting of both species, in a freezer for two minutes. While only half of the golden silk spiders survived, 77% of the Joros made it through the two minutes of cold.
The results of the study, combined with the speed at which the Joro spider can mate and reproduce, tells us that the species is likely to thrive in the winter seasons in the northern parts of the U.S. “The jorō spider is here to stay,” says Frick. And since we're unsure of how the invasive species might impact our ecosystem, we have a feeling this isn't the last we'll hear about this newcomer. Be sure to stay tuned as scientists find out more about the Joro species!