It is difficult for light to penetrate the dark depths of the ocean, and animals have found a variety of adaptations to live and hunt there. Whales and dolphins, for example, use sonar – the art of sending clicks into the water and hearing their echoes as they bounce off potential prey to locate them. But deep-sea seals that do not have the same acoustic headlights must have evolved to develop another sensory technique. Scientists have long speculated that the secret weapons are their long, cat-like mustaches, which have been conducting more than 20 years of experiments with artificial whiskers or captive seals blindfolded in a swimming pool, given the difficulty of direct observation by hunters in the dark. depths of the ocean. Now a study may have confirmed the hypothesis, according to Taiki Adachi, assistant professor of program at the University of California, Santa Cruz, and one of the lead authors of the study, published in the Proceedings of the National Academy of Science. Adachi and his team installed small video cameras with infrared night vision on the left cheek, lower jaw, back and head of five free northern elephant seals, Mirounga angustirostris, in Año Nuevo State Park, California. They recorded a total of about nine and a half hours of deep sea footage during the seasonal migration. Adachi and his team installed small video cameras with infrared night vision on the left cheek, lower jaw, back and head of five free northern elephant seals, Mirounga angustirostris, in Año Nuevo State Park, California. They recorded a total of about nine and a half hours of deep sea footage during the seasonal migration. Analyzing the videos, the scientists observed that the diving seals held back their whiskers at the beginning of their dive and, as soon as they reached a depth suitable for food, they rhythmically flushed their whiskers back and forth, hoping to feel any vibration caused. from the slightest movement of prey water. (Elephant seals like to nibble on squid and fish and spend a lot of time in the sea.) Then, as they swam back to the surface, their whiskers curled back toward their faces. For less than a quarter of the time the seals were hunting, they could also see some bioluminescence – the light that some creatures deep under water can emit thanks to the chemicals in their bodies – to locate their meals using their eyesight. . But for the remaining 80% of their hunting spree, they were apparently just using their mustaches, according to Adachi. This technique is not similar to rodents, Adachi noted. Simply because water is much denser than air, the stirring speed is much slower in elephant seals. “That makes sense,” said Sascha Kate Hooker, a finned researcher at the Marine Mammal Research Unit at St Andrews University, who did not participate in the study. “Among deep-sea marine mammals, elephant seals reach the same depths as sperm and whales with beaks, often well over a mile below the surface.” Guido Dehnhardt, director of the Marina Science Center at Rostock University and a pioneer in mustache research who did not participate in the study, welcomed the findings, but was careful about how much new information they represented. “It was my team that showed more than 20 years ago that seal whiskers represent a hydrodynamic receptor system and that seals can use it, for example, to detect and track hydrodynamic traces of fish,” he said. Dehnhardt. Subscribe to the First Edition, our free daily newsletter – every morning at 7 p.m. BST The study is particularly interesting from a technical point of view, especially considering that the cameras used are so small, Dehnhardt said, but there is still a lot of speculation. “It would be a wonderful story if the seals, in addition to a camera mounted on the head, wore a hydrodynamic measuring system. [a machine that can measure the movement of fluids] so that the movements of the musts and the hydrodynamic events can be correlated “. In the future, Adachi would like to begin comparing the way other mammals use their whiskers to better understand how the superpowers of certain animal wolves have shaped food-seeking habits in the animal kingdom.
