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Some mammals may use specialized hairs to detect heat from predators

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IIn addition to their acute senses of smell, hearing and sight, small mammals may have an additional method of detecting predators: heat-sensitive guard hairs capable of picking up infrared radiation emitted by hot bodies, suggests a study. The new research, published last week (December 8) in Royal Society Open Science, is based on a body of unpublished evidence gathered not by a biologist, but by a physicist, Ian Baker, who develops infrared sensors for a British defense company.

Baker took his work home for a long time, he says The New York Times, using infrared cameras containing his sensors to scan fields and woods near his home in Southampton, England, for animals. for animals. A series of anecdotal observations – such as cats appear to ‘stack’ their bodies behind their cold noses when hunting, as well as similar twisting behavior in diving owls – led Baker to hypothesize. that these predators “may need to hide their infrared. to be able to catch a mouse ”, in fact“ hiding their heat ”.

Predators such as cats and owls modify their behavior during the hunt, perhaps to hide their heat signature from potential prey.

As part of his investigation, Baker put mouse hairs under a microscope, and what he saw immediately seemed familiar to him, he told the Time. The mouse’s guard hairs, the long, coarse strands that form a protective layer on an animal’s undercoat, resembled the structures it often saw in its sensors. Specifically, the bristles contained evenly spaced bands of pigment that, in a sensor, allow the instrument to focus on specific wavelengths of light.

The scratch measurement supported the idea that, just like with a thermal imager, hair appeared to match the 10 micron wavelength of light, the thermal signature emitted by many living things. “It was my Eureka moment,” Baker told the Time.

Following his discovery, Baker documented similar hairs in shrews, squirrels, rabbits and other species, some with even more complex guard hair structures that suggest “really sophisticated optical filtering.” If such hairs can actually sense heat, it would mean that many species have a 360-degree sensory shield.

Tim Caro, a professor of evolutionary ecology at the University of Bristol in England who was not involved in the work, tells the Time that the study paints an “intriguing picture”. Helmut Schmitz, a researcher at the University of Bonn in Germany who studies the infrared detection capabilities of insects, calls the results “plausible”. But the two researchers note that more study is needed to link hair structures to function. One direction, Schmitz says, would be to confirm that the skin cells at the base of the hairs can actually detect tiny temperature changes.

Baker continued to study the behaviors of animals near his home that might support his hypothesis. He recently developed a pair of “hot eyes” made up of sensors believed to mimic the eyes of an owl and uses them to study how rats react to the simulated predator’s gaze, although this work has not been published, according to the Time. Furthermore, Baker adds that he hopes to see others pick up on his work to study the phenomenon in more detail. “Animals that operate at night have secrets,” he told the Time. “There must be a huge amount that we don’t understand.”