Watch how battles with bats give moths their flashy tails | Science

Bats and their prey are in a constant arms race. While winged mammals harbor insects with frighteningly precise sonar, some of their prey – like the tigress tigress – struggle with sonar clatter and even jamming signals. Now, in a series of bat skirmishes (above), scientists have shown how other moths create an "acoustic illusion," with long tail tails that deceive the bats in the wrong place. The discovery helps to understand why some butterflies have such showy tails, and this can also inspire the drones of the future.

The tails of butterflies vary from one species to another: some have large lobes below the hindwing; ; others have just a short protrusion. Still others have long tails that are thin strands with crooked cuplike ends. In 2015, sensory ecologist Jesse Barber of Boise State University in Idaho and her colleagues discovered that some silk butterflies use their tails to confuse bat predators. Now, graduate student Juliette Rubin has shown what makes tails so effective.

Working with three species of nocturnal butterflies: the luna, the African moon and the polyphemus, Rubin shortened or cut out some of their hindwings and stuck them longer. form tails to others. She then tied the moths to a string hanging atop a large cage and released a large, brown bat ( Eptesicus fuscus ) inside. She used cameras and high-speed microphones to record the fight that ensued.

Tailless mites (such as polyphem) were an easy career for bats, escaping only 27% of the time, report today Rubin, Barber and his colleagues in Science Advances . But when Rubin enlarged the polyphemus lobe, twice more escaped the bat sonar or the echolocation system.

Bats chasing long-tailed African moths took a tail bite 75% of the time. Shorten the tail, and the African moon mites escaped only 45% of the time. With no tail at all, this percentage dropped to 34%. When Rubin built a family tree of moths and their parents, she realized that long tails had evolved independently several times. "The authors have demonstrated a powerful approach to understanding the diversity of forms of the moth," says Aaron Corcoran, an animal ecologist at Wake Forest University in Winston-. Salem, NC, who was not involved in the job. "There seems to be many ways to deceive the echolocation system of a bat." The study also revealed how difficult it was for bats to bypass this deception, he added. "The fact that the bats in the study never learned how to catch these mites, despite the time needed to do so, shows how much this blind spot is wired into the perception of the bald mouse."

Robotics, explains Martin How, sensory ecologist at the University of Bristol in the UK. Because the study examined bat flying fights on such a fine scale, the results could help engineers design "bio-inspired technologies for the future," he says, including flying drones skillfully.