Most species of shark need to remain in constant movement to keep water flowing over their gills, or else they'll suffocate. But like all animals, sharks still need to sleep. So how do they snooze when they need to swim?
Interestingly, very few shark species have ever been witnessed sleeping, and many scientific mysteries still exist around shark shuteye. A new video (clip shown above) that is premiering for Discovery's 2016 Shark Week could finally answer some of these questions.
The remarkable footage was captured by a robotic submersible that tracked a female great white shark as it swam at night around Guadalupe Island, near Mexico’s Baja California Peninsula. It is believed that this is the first time a great white has ever been caught on camera in a sleep-like state.
As night fell, the shark altered its behavior to swim close to shore in shallow waters. The route it took faced straight into strong, oxygen-rich currents with its mouth wide open, likely so that the water could continue to flood over its gills with a minimal amount of exertion.
Although it's probably terrifying to imagine a mammoth great white shark swimming in shallow waters in the dark of night with its mouth wide open (it's enough to make you think twice about that midnight skinny dip!), this might actually be the safest time to swim with one of these apex predators. Though the shark continued to swim, it seemed to be in a catatonic state, as if hypnotized. Researchers believe that this is what a great white looks like when it's sleeping.
Previous research has suggested that a shark's swimming motion is actually coordinated by its spinal cord, not its brain. This may be how they manage to fall asleep while continuing to move; their brain naps while their bodies still sway, propelling them forward.
It's a fascinating find, one which displays a vulnerable side to these carnivores of the deep.
Sharks so often occupy our nightmares, but now we're left to wonder: What might occupy theirs?