Scientists 3D print black widow spiders to learn the secret behind its red hourglass

Mar 2, 2016 | By Tess

Everyone has heard of the black widow spider, one of the most venomous spiders in the world, whose bite could seriously harm a human and kill most animals. The spider’s signature red-hourglass mark which stands out from her stark black body would surely make anyone jump back in fright. It turns out, however, that the spider’s bright red mark is not just meant to scare us humans away, or to invade our nightmares, but to communicate secret warning signals to certain species of animals.

Researchers supported by Duke University recently conducted tests using 3D printed fake spiders to test what effects the black widow’s red mark had on different animal species, namely birds and insects, with the goal of determining how the spider’s marks have different effects on the two types of animal.

The study, which was posted on February 27th in Behavioral Ecology, used 3D modeling and 3D printing technologies to create realistic black widow models. The spider model’s design came from a 3D model designed by video game developers, who often include the venomous spider in their game design to create fear and spooky environments.

For the tests, eight spider models were 3D printed, four of which were painted black and four of which bore the unmistakeable red hourglass mark of the black widow on their bellies. To gather data, the fake spiders were placed with their bellies facing upwards in various local bird feeders in Durham, North Carolina to see how hungry birds would react. According to the study’s findings, birds were three times less likely to fly up to and try to feed on a spider bearing the red marking, with smaller birds even jumping back in fear when the mark was spotted. Lead author of the report Nicholas Brandley said, “The birds would see a spider model with red markings and get startled and jump back, like ‘Oh no man, get me out of here.”

The research also found that the black widow’s positioning, typically with her red belly facing to the sky, deterred birds who were flying overhead, but made little difference to insects crawling towards her from below. To more thoroughly test this idea, the researchers compared two types of North American black widows, one with a red mark only on its belly and one with red marks on the belly and back, to see how their web building behavior varied. The black widow with both markings on her belly and back tended to build web higher from the ground, thus necessitating marks on her front and back to warn birds away from both sides, while the spider with marks on her belly built her web much closer to the ground, only needing to deter birds from above.

Of course, sight has a lot to do with how both birds and insects respond to the black widow’s marked danger as well. After testing how each species would perceive the red hue of the spider’s markings using a spectrodiometer, the researchers found that birds perceived the red hues with two times more contrast than insects could, making the spider much more visible to the spider’s potential predators rather than its prey.

The recent study once again demonstrates the varied and exceptional uses of 3D printing technology. This time, the ability to easily create lifelike models of a spider species has helped in to give us insight into a feared species of animal, the black widow spider.

Posted in 3D Printing Application

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Scientists 3D print black widow spiders to learn the secret behind its red hourglass

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