![]() Since the spider hitchhiked its way to the northeast of Atlanta, Georgia, inside a shipping container in 2014, its numbers and range have expanded steadily across Georgia, culminating in an astonishing population boom last year that saw millions of the arachnids drape porches, power lines, mailboxes and vegetable patches across more than 25 state counties with webs as thick as 10 feet (3 meters) deep, Live Science previously reported.Ĭommon to China, Taiwan, Japan and Korea, the Joro spider is part of a group of spiders known as “orb weavers” because of their highly symmetrical, circular webs. “If they‘re literally in your way, I can see taking a web down and moving them to the side, but they‘re just going to be back next year.” “People should try to learn to live with them,” lead author Andy Davis, a research scientist at the University of Georgia, said in a statement. This has led scientists to suggest that the 3-inch (7.6 centimeters) bright-yellow-striped spiders - whose hatchlings disperse by fashioning web parachutes to fly as far as 100 miles (161 kilometers) - could soon dominate the Eastern Seaboard. 17 in the journal Physiological Entomology, suggests that the palm-sized Joro spider, which swarmed North Georgia by the millions last September, has a special resilience to the cold. Lab tests used only the conveniently big jorō females, though male ability to function in random cold snaps could matter too.New research, published Feb. ![]() And about two minutes of freezing temperatures showed better female survival (74 percent versus 50 percent). Checking jorō oxygen use showed females have about twice the metabolic rate. He has measured heart rates of monarch caterpillars, and he found a spot on a spider’s back where a keen-eyed observer can count throbs.įemale jorō spiders packed in ice to simulate chill stress kept their heart rates some 77 percent higher than the stay-put T. The jorō sluices its bloodlike fluid through a long tube open at both ends. ![]() But how do you do that with an arthropod with a hard exoskeleton? A spider’s heart isn’t a mammallike lump circulating blood through a closed system. (The jorō also can spin yellow-tinged silk.) The earlier arrival’s flashy females and drab males haven’t left the comfy Southeast they invaded at least 160 years ago.įiguring out the jorō’s hardiness involves taking the spider’s pulse. These new neighbors inspired Davis and undergraduate Benjamin Frick to see if the newcomers withstand chills better than an earlier invader, Trichonephila clavipes, their more tropical relative also known as the golden silk orb-weaver. A female jorō spider looms so much bigger that it’s easy to overlook the males of the species (inset, shown to scale) that often hang out in her big web. “One big web can be 3 or 4 feet in diameter.” Jorō spiders have lived in northeastern Georgia since at least 2014. “I’ve got dozens and dozens in my yard,” says ecologist Andy Davis at the University of Georgia in Athens. When it comes to humans, these spiders don’t bother anybody who doesn’t bother them. Males being merely half size or thereabouts might explain the relatively peaceful encounters. As far as Kuntner knows, however, jorō spiders don’t engage in these “sexually conflicted” extremes. With such extreme size differences, mating conflicts in animals can get violent: females cannibalizing males and so on ( SN: 11/13/99). The most dramatic case Kuntner has heard of comes from Arachnura logio scorpion spiders in East Asia, with females 14.8 times the size of the males. ![]() The group shows the most extreme size differences between the sexes known among land animals, says evolutionary biologist Matjaž Kuntner of the Evolutionary Zoology Lab in Ljubljana, Slovenia. Mismatched sexes are nothing new for spiders. ![]()
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