ATHENS, Ga. — New research by the University of Georgia and its partners shows that an invasive species of arachnid in the state of Georgia may be not so as demure as previously believed.
Researchers working with the university said in the study that they normally describe the Joro spiders as a “shy” species, at least shy compared to their America-native peers.
The researchers newer observations show, however, that the species might also be cannibals.
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That’s right, the Joro, a non-native species of spider from Japan and other parts of East Asia, has been in Georgia for several years now.
The study noted that Joro spiders have been spotted webbing their way around the southeast United States since 2014 and have been expanding their range since.
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An orb weaver, Channel 2 Action News has reported on how the spiders have a somewhat unique form of travel: using their webs to spin parachutes and travel on the wind.
The recently published study by UGA scientists, titled "It’s a Spider-Eat-Spider World," noted that unlike some species of spiders, where the females cannibalize males during or after mating, the Joro is different.
Through a series of experiments and lab tests, the researchers found that cannibalism was at times more related to territorial aggression, rather than sexual activity.
"In the cases where cannibalism was witnessed, it involved one female biting and killing another, typically after a short fight. When two females of a similar size were placed together in a container, fights ensued 40% of the time," according to the study. “When females of different sizes were paired, fights happened 18% of the time, and the larger females were not always the aggressor.”
The study also found that fights between spiders would happen even when they were not on a web together, implying that the aggression may not necessarily be over territory.
During research on the spiders, observers in Clarke County said while performing unrelated research on Joros, three of the study’s authors watched two spiders begin fighting immediately upon being released near each other, leading to one’s death.
Out of 52 tests of fights set up between spiders of different sizes, researchers said six “led to obvious cannibalism,” but there was not a clear effect of body size to aggression.
Small spiders and larger spiders both started fights.
Of an additional 14 tests of spider fights, there was one example where a female spider killed another female spider, then wrapped it in silk, what the scientists said was akin to marking the other arachnid as “prey.”
The researchers said the aggressive behavior was interesting specifically due to the “shy” nature of Joros in previous observations.
The observed conflicts also spun counter to the “tendency of spiders of this genus to form ‘communal’ webs, which we have observed in Georgia,” the study authors said.
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