- Elephant seals drift downwards in a “sleep spiral” when deep diving within the ocean, a brand new examine discovered.
- Sleeping whereas deep diving permits the seals to keep away from predators, scientists consider.
- The scientists recorded the mind waves of 13 younger feminine seals in California as a part of the examine.
Elephant seals drift downwards into the ocean in a “sleep spiral” to atone for sleep whereas on months-long foraging journeys however are programmed to not drown, in accordance with a brand new examine.
The seals fall into sleep throughout deep dives of as much as 377 meters, which is round 1,235 ft, to keep away from predators. They spiral downwards for about 10 minutes at a time throughout half-hour dives, and so they generally even catch some sleep on the ocean ground, in accordance with new findings revealed in Science.
The examine marks the primary time scientists have studied the mind waves and recorded the sleeping habits of a free-ranging, wild marine mammal, in accordance with the College of California, Santa Cruz.
The examine examined the essential nature of sleep for mammals, and identified that marine mammals “encounter particularly difficult circumstances for sleep when they’re at sea.”
“For years, one of many central questions on elephant seals has been when do they sleep,” Daniel Costa, director of the UCSC Institute of Marine Sciences, mentioned.
The lab used tags to trace the actions of elephant seals within the Año Nuevo Reserve when the animals head out to the Pacific Ocean for months at a time.
“The dive data present that they’re continually diving, so we thought they have to be sleeping throughout what we name drift dives, after they cease swimming and slowly sink, however we actually did not know,” Costa continued.
Professor Terrie Williams, from UC Santa Cruz, informed BBC Information that it was “outstanding” that any mammal would go to sleep whereas drifting lots of of ft beneath the water floor.
“This isn’t mild sleep however actual paralytic, deep sleep that will have people loud night breathing. Remarkably, the seal’s mind reliably wakes them out of it earlier than operating out of oxygen.
“Think about waking up on the underside of a pool – it sends a shiver down the backbone,” mentioned Williams.
African elephants presently maintain the title of mammal that sleeps the least, at simply two hours a day, however these new discovering present that elephant seals “rival the document,” in accordance with UCSC.
Killer whales and sharks assault elephant seals when they’re on the floor of the ocean, which is why they spend so little time close to the highest and solely take a short while respiratory on the floor between dives, per UCSC.
“They’re in a position to maintain their breath for a very long time, to allow them to go right into a deep slumber on these dives deep beneath the floor the place it is protected,” mentioned Jessica Kendall-Bar, who led the examine.
The scientists fitted neoprene headcaps with electroencephalogram (EEG) sensors to document the 13 younger feminine seals’ mind exercise.
“We used the identical sensors you’d use for a human sleep examine at a sleep clinic and a detachable, versatile adhesive to connect the headcap in order that water could not get in and disrupt the indicators,” Kendall-Bar, a postdoctoral fellow at UC San Diego’s Scripps Establishment of Oceanography, mentioned.
The recordings confirmed the diving seals going right into a sleep stage generally known as “slow-wave sleep” earlier than transitioning into REM sleep, which ends up in a form of “sleep spiral” or sleep paralysis, specialists discovered.
Elephant seals do get numerous sleep when they’re on land — about 10 hours — scientists mentioned, which makes their sleeping sample “uncommon.”
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