More than 30 adult sperm whales are sleeping at 15 meters in the Indian Ocean. They stand like this for minutes or even hours without moving. All of them are female, and while the parents sleep, all of the calves are at the surface.
When one of the biggest animals in the ocean sleeps, it can look strange.
There are popular pictures of sperm whales standing still in the water in a vertical line that has been posted online. The whales, are about the size of school buses. And seem to be “standing” and grouped in pods of five or six almost all of the time.
Stephane Granzotto, a French photographer and filmmaker, saw this while diving in the Mediterranean to take pictures of sperm whales for his photo book called Cachalots. In the photo above, which he sent to National Geographic’s YourShot photography community, he wrote that the whales had been sleeping for an hour.
The first study to show that whales sleep on their backs was published in 2008 in the journal Current Biology.
Scientists had seen some captive cetaceans sleep by watching their eye movements, but they didn’t know much about how whales slept in the wild. Researchers from the University of St. Andrews and the University of Tokyo put data-collecting tags on 59 sperm whales and measured when the animals were not moving.
Seven percent of the whales’ day was spent in these vertical sleeping positions near the water’s surface. They slept for 10 to 15 minutes at a time. Researchers thought they might be one of the animals that needs the least amount of sleep.
Scientists have found that whales in captivity use only half of their brains when they sleep. This could help them avoid…