Narwhals 'See' Unlike Any Other Species
Directional sonar helps them find areas free of ice
By Arden Dier,  Newser Staff
Posted Nov 10, 2016 7:25 AM CST
A pod of narwhals swim off the coast of northern Canada.   (AP Photo/APL/University of Washington, Kristin Laidre)

(Newser) – Whales need to surface in order to breathe, and the narwhal is no different. Every four to six minutes, the Arctic whale—including males with a long tooth resembling a horn—must emerge from the depths of Baffin Bay between Baffin Island and Greenland, where 80% of all narwhals winter, and find tiny openings in the ice, reports the New York Times. "You don’t see open water for miles and miles and suddenly there’s a small crack, and you’ll see narwhals in it," says the lead author of a new PLOS study. "I’ve always wondered how do these animals navigate under that, and how do they find these small openings to breathe?" The answer, it turns out, is remarkable. Narwhals use the most directional sonar of any species, sending up to 1,000 "clicks of sound" per second through their heads, then directing the clicks into a beam, focusing on prey like fish and squid in the Arctic depths, or sections of open water amid an icy surface.

After placing underwater microphones at 11 pack ice sites in Baffin Bay, per a release, researchers found narwhals made a wide scan of an area through echolocation, but could also narrow their sound beam into "the most directional biosonar signal reported for any species to date." Think "a spotlight rather than a floodlight," per Cosmos. In directing the signal up, narwhals have a clear "view" of surface areas free of ice. "It is not like a singing humpback whale that spreads the sound widely and can be heard over long distances," says an ecologist not involved in the study. The downside: Researchers say narwhals' echolocation may suffer as noisy ships, including those with sonar, enter their habitat. Adds the ecologist: "Narwhals are living a secretive life in the Arctic, but this study has unveiled one of the secrets from the deep waters in the Arctic." (A narwhal's tusk may suggest the size of its testicles.)
 

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