It's just so fascinating!
Sperm whales are one of the largest animals in the ocean, which makes everything about them rather fascinating. However, a report by Nat Geo revealed that the way they sleep is quite mesmerizing, because they do so in a vertical position. The whales are so huge that they're about the size of school buses, and they almost always appear to be "standing" and clustered in pods of five or six.
French photographer and filmmaker Stephane Granzotto captured mesmerizing photos of whales sleeping vertically while he was diving in the Mediterranean sea. So, when exactly do they sleep?
Apparently, when sperm whales feel tired, they dive down about 45-feet below the surface of the sea, get ready for bed vertically, and catch some zzzz's. A quora post by David M. Prus gives a bit more detail into why sperm whales sleep like this: Not all whales sleep vertically, but those who do, namely sperm whales, do so using the light as a point of orientation. They point their snouts to the light, knowing that if they are low on air, they will automatically wake up. Sleeping vertically allows them to grab a quick breath of air if they really need it. It also helps that they have very light noses, and can change the shape and consistence of the fluids in their noses like submarine ballast in order to go up and down.
Active hunting means diving, so they make the mass in their head denser. When they need to surface, they make their noses lighter. Keeping their noses light doesn’t take much conscious effort, and it’s closer to the sunlight, so that makes sleeping nose-up natural.
In 2008, a study published in the journal Current Biology was the first to document the whale's vertical sleeping position. For the study, data-collecting tags suction were cupped to 59 sperm whales. Researchers from the University of St. Andrews and the University of Tokyo measured the animals' periods of inactivity.
That's when they found out that these whales spent about 7 percent of their day sleeping, in vertical position, near the surface of the water and they napped for 10-15 minutes. At the time, researchers also suggested that sperm whales might be one of the world's least sleep-dependent animals.
Apparently, whale in captivity use only half their brain while sleeping and this is mostly because it could help them avoid predators, maintain social contact, control breathing, or continue swimming, believe behavior scientists. Whatever the reason may be, it simply is fascinating to note the way sperm whales sleep.
While the 2008 study was the first to conclusively prove that sperm whales slept in a form of suspended grace in the ocean, it was not until 2017 that the world got to see just how beautiful and hypnotizing this looked. It was French photographer and filmmaker Stephane Granzotto who first captured this in the Mediterranean sea while documenting the behavior of sperm whales for his photo book, Chachalots. He submitted the photos to the YourShot photocommunity of National Geographic in 2017. It showed a group of sperm whales that had been asleep for about an hour. You can check out the photos here.