The robotic snakes that could teach us about animal behavior
Robotic mimics of venomous snakes could help researchers understand predation in the Amazonian rainforest
Talia Moore is afraid of snakes. And sometimes for good reason — the coral snakes she studies use venom to suffocate potential predators by paralyzing their breathing muscles. But now Moore can rest easy, because she and other researchers at the University of Michigan have created robotic snakes to safely study their venomous counterparts.
Moore’s research focuses on how animal movement has evolved over millions of years, and she finds coral snakes particularly interesting because they have an unusual way of moving when they’re threatened. While some snakes raise their heads and hiss to warn off other animals, coral snakes contort their bodies with a thrashing motion.
Moore wants to know how effective this thrashing is for deterring predators, and if there are venom-resistant animals that will attack coral snakes despite their threatening behavior. But live coral snakes are dangerous to work with, and it’s hard to make them thrash on command. So Moore and her coworkers built robotic snakes that they’ll bring to the Amazonian rainforest, where they hope to learn how coral snakes interact with potential predators.
Daniel Bruder is an engineering graduate student who designed Moore’s robotic snakes using a kind of soft robot that his lab is refining. “They’re made of elastic tubes, kind of like one of those balloons that you get at the circus,” Bruder said. By wrapping fibers around these tubes, Bruder constrained the shapes the tubes could take on when inflated, causing them to mimic the kinks and curves of a threatened coral snake.
To make the robot, Bruder needed examples of how live coral snakes move, so Moore swallowed her fear and waded into the Amazonian rainforest during the rainy season to catch some. “It’s kind of miserable,” Moore said of the forest. “It rains every day, and you slosh through.” Moore’s video cameras, which had been advertised to her as “rugged,” overheated frequently in the muggy weather, frequently delaying her research. Yet despite the discomfort and technical glitches, Moore managed to trap dozens of snakes, including coral snakes. She then recorded their behavior as she waved cloths over them to simulate birds attacking from above and put vibrating cell phones near their enclosures to simulate mammalian predators approaching.
Back in the lab that Bruder works in, where Moore has long collaborated with him and other engineers, Moore outlined on a whiteboard her plan to turn snake videos into snake robots. Shannon Danforth, an engineering graduate student, realized she could use her video analysis skills to measure the curvature of the snakes as they thrashed, and offered her services. With Danforth’s help, the team measured precisely how much the live snakes curved, and compared these measurements to the robots — a level of quantitative detail that Moore said “is rarely done in biomimetic or bio-inspired robotics.”
Moore plans to deploy these robots in the Amazonian rainforest and see if any animals attack them. Researchers have done similar experiments using clay models of snakes, and found that painting these models with the bright pattern of a coral snake makes them less appealing to predators. Moore’s robots will also mimic the colors of live snakes, but she and her team will be the first researchers to add movement into the mix. Deploying her robots in the wild will let Moore test whether their thrashing behavior further deters predators.
Stephen Mackessy researches venomous reptiles at the University of Northern Colorado, and was not involved in this study. He envisions one day using robotic snakes to penetrate snake dens and record video that will give researchers insight into habitats that are impenetrable to humans. “Having the capacity to send something down a small opening and record what things look like underground would be fascinating,” he says.
No matter how they’re used, the robotic snakes will have to work on their moves. Undercover robotic snakes that can sneak into dens will require a wider range of motion than Moore’s snakes currently possess. And for Moore’s experiments, if the robotic snakes always move in the same way, Mackessy thinks predators may lose interest in them. Bruder is extending the range of motions that his soft robots can use, but more motion requires more electronics. For research in the harsh conditions of the Amazon, he thinks a simple snake will be least likely to break.
Moore and her collaborators are eagerly awaiting the end of the pandemic so that they can travel to the Amazon and see how wild animals react to their snakes. “We are ready to do tests,” she said. “It’s just a matter of getting access to the predators again.”
