Sperm whales sleep vertically and other interesting facts

Posted by Anita Froneman on 19 July 2021

Whales are fascinating animals, and sperm whales are particularly interesting in that they have been found to sleep in an upright position.

First detected in 2008, researchers published their findings in the journal Current Biology, stating that sperm whales were recorded drifting in pods in a vertical posture just below the surface for about 15 minutes at a time, during which they did not breathe or move. In fact, they were completely unaware of the research team observing them. The study showed that these giants spent about 7% of their time drifting sleepily in this way.

According to Nature, sperm whales likely choose between two types of sleep: full sleep while drifting at the surface, and half-sleep, depending on their needs. ‘This finding raises the possibility that in the wild, cetaceans have flexibility in the type and depth of sleep that they enter, which is intriguing because this is behaviour that we have seen in birds too,’ said Niels Rattenborg at the Max Planck Institute for Ornithology in Germany.

Watch this explainer video:

Sperm whales are the world’s largest toothed whale, growing to over 16 meters long, according to Oceana. They also have the most powerful sonar of any animal, used for hunting.

Sperm whale female and calf. Credit: Wikimedia Commons

They are some of the ocean’s deepest divers, reaching up to 1000 meters deep and and can stay underwater for up to two hours. They are currenty listed as Vulnerable by the IUCN.

These whales are found in deep open oceans across the globe, and have also been sighted in South Africa before, according to the Whale Watching Handbook.

Picture: Screenshot from YouTube

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