Northern elephant seals are champions in taking power naps
Do you know what power naps are? Yes, they refer to a short sleep taken during the daytime in order to refresh an individual and generally terminated before deep sleep begins, so as not to leave the sleeper drowsy. Now, are you a master in taking power naps? Well, it is indeed a necessary trait. But not everyone has it, unless of course it is a Northern elephant seal.
Yes, you read that right. Turns out, this species of seals slumber for less than 20 minutes at a time especially while taking long trips. This was recently revealed by researchers based at University of California who published a paper in the journal Science. They have also reported how the animals have the tendency to swim offshore for months, during which they hardly sleep two hours a day. This matches the sleep pattern of African elephants that sleeps the least as noticed among mammals.
Experts suggest that this study was significant in order to understand evolution and the function of sleep in mammals, including humans. Not only that, figuring out where these seals nap can also help in conservation efforts, in order to secure the places where they take them.
For those unaware, Northern elephant seals are native to the Pacific Ocean where they forage round the clock for fish, squid and other smaller marine animals to sustain themselves. After all, they have mammoth physique, almost the size of a truck. What’s interesting is that, despite that, they often fall prey to sharks and killer whales at the surface, which is why they mostly spend their times deep underwater and only come up for a couple of minutes between their 10- to 30-minute-deep dives.
Earlier, their unique dive patterns were known to the scientists, but how long they sleep and why were still a mystery, as revealed by Niels Rattenborg of the Max Plank Institute for Biological Intelligence, Germany, who was not part of the study.
Interestingly, to figure out whether the seals sleep while diving, the researchers involved created a watertight EEG cap for the animals. Using the cap, they tracked the brain waves, heart rates and 3D motions of 13 young female seals, 5 at the lab and the rest at the Ano Nuevo State Park, California. Depending on the slower brain waves and heart rates, the scientists could map when they napped. Besides, two EEG capped seals from the park were also released at a beach, 60 km south. From there, they swam across the deep Monterey Canyon and spent months on their foraging trips. Once they returned, the scientists matched the EEG readings with their diving motions that proved how they slept during long voyages.
Okay, so what was observed. That they at first go 60 to 100 metres down and then go into power naps in upside down position, away from the region where their predators roam. But they only slumber for 5 to 10 minutes, after which they again start swimming. This process keeps on repeating and the whole thing takes about 20 minutes.
What is more interesting is a similar sleep pattern was noticed among great frigate birds. Apparently, they fly over the ocean and can sleep during that time for a few minutes and then resume their flight.