![]() ![]() The sharks occasionally slept with their eyes shut, though mostly during the day. But when the sharks fell asleep, the researchers noticed the fish changed their posture by flattening and nestling closer to the ground. “We know that a drop in metabolism is a telltale sign of sleep in many, many other animals,” Kelly tells the Guardian’s Donna Lu.īecause draughtsboard sharks are ambush predators, the three-foot-long animals usually position themselves with their fins out and head up. When the sharks were resting for five minutes or longer, their oxygen consumption dropped, suggesting the animals are drifting off to sleep. To see if the animals were in fact asleep, the team analyzed the metabolism and posture of seven draughtsboard sharks over 24 hours. Unlike great whites and tiger sharks, which must keep swimming to ventilate their gills, draughtsboard sharks are a species of buccal pumping sharks, which manually push water over their gills to take in oxygen while stationary. In their study, the team of scientists observed draughtsboard sharks, a nocturnal shark native to New Zealand, apparently sleeping during periods of rest. “Sharks are a particularly important group as they are the oldest living jawed vertebrates-a trait they share with us.” ![]() "Until now, sleep in sharks was completely unstudied and unknown,” says study author Michael Kelly, an ecophysiologist at La Trobe University, to Robyn White for Newsweek. Scientists in Australia have now documented a species of bottom-dwelling shark sleeping for the first time, upending the long-standing debate. Sharks can sleep, and often opt to keep their eyes open while they do, according to new research published in Biology Letters.īecause some sharks must swim constantly to keep oxygen-rich water flowing over their gills, it has long been rumored that they don't snooze at all.
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