Scientists have studied the nocturnal New Zealand cat shark and found that when resting for more than five minutes, these sharks have reduced oxygen consumption, which is an indicator of sleep. The study was published in the journal Biology Letters.
It was previously thought that sharks needed to be constantly moving in order to breathe, which is why they never sleep.
It is reported that scientists planned to determine the metabolic signs of sleep and track sleep indicators such as closing the eyes and changing body position (lying down). The researchers observed the sharks for 24 hours.
As a result, sleep phases in cathead sharks have been identified that have been associated with lower metabolic rates. In addition, according to biologists, sharks took a more “flat” posture during sleep. Now the scientists plan to study in more detail how sleep affects their brain activity.
According to the observations of experts, sleeping sharks more often closed their eyes during daylight hours. Perhaps this is not due to the state of sleep itself (that is, they do not prefer to sleep with their eyes closed, like other animals), but to external factors, such as the presence of light.
It is noted that laboratory experiments conducted back in the 1970s showed that dog sharks can move and sleep at the same time. To do this, they “turn off” the brain, allowing the spinal cord to control the movements of the body.
In the near future, as noted, scientists will analyze the behavior of other sharks
