(ORDO NEWS) — Some species of sharks are known to need to constantly move in order to breathe, but researchers say they can sleep even while they are moving. The results of this study were published in Biology Letters.
Sharks sleep just like us, debunking the misconception that they never sleep because they have to keep moving to keep from dying, according to a new study.
“We have provided the first physiological evidence for sleep in sharks,” a team led by ecophysiologist Michael Kelly of the University of Western Australia writes in a new paper.
It is true that many shark species must keep moving in order to obtain oxygen, but whatever method they use to breathe, sharks may participate in periods of deep rest but do not fall asleep in the traditional sense.
The team examined sleep patterns in the checker shark, which they had previously found to be nocturnal animals.
In a previous study, scientists confirmed that sharks have periods of rest. However, they did not confirm that these quiet periods were indeed a dream.
When monitoring the sharks for 24 hours, it was found that their oxygen levels were constantly decreasing during periods of rest. Periods that last more than five minutes are sleep, the study says.
“Sleeping sharks not only have reduced sensitivity to electrical stimulation, but also have lower metabolic rates,” explains Kelly and team.
Sharks closed their eyes during sleep most often during the day. During the night, 38% of sharks kept their eyes open.
Great white sharks have to constantly swim forward to force oxygenated water into their mouths and over their gills, this is called ventilation.
It is possible that ventilated sharks can continue to swim without being conscious due to the mechanisms that control swimming movements located in the animal’s spinal cord rather than the brain.
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