How Do Whales Sleep? Fin-tastic Facts Explained For Kids

Ayan Banerjee
Feb 07, 2023 By Ayan Banerjee
Originally Published on Nov 10, 2021
Edited by Katherine Cook
Fact-checked by Nishtha Dixit
Sperm whale off the coast of Roseau.

The biggest mammals in the world are whales.

Whales are categorized as one-toed ungulates along with dolphins and porpoises. They belong to the clade of Cetaceamorpha.

A whale is an ancient mammal species that possibly originated 34 million years ago. Presently, sperm whales are the largest tooth predator animals on earth.

Although whales live in water bodies, they evolved from land-living animals, meaning they have to regularly come out of the water to breathe oxygen. They are warm-blooded similar to humans.

A whale's body has a thick layer of fat protecting it from cold waters. They may consciously swim, and also avoid predators or social contact during the period of rest and sleep. The population of whales is at threat as their number is decreasing day by day.

Global climate change, increase in water temperatures, and lack of food are big threats to them. Big whale species like humpbacks and blues have to cover long distances to reach the feeding grounds, leaving less time to digest the food.

If you enjoyed this article then why not learn amazing and interesting facts about Pygmy Beaked Whale Facts and how do whales drink milk underwater at Kidadl.

Do all whales sleep in the same way?

All whales and dolphins sleep in the ocean. The methods and requirements for marine animals when sleeping and resting are different from that of land animals.

Whales are cetaceans with conscious respiratory systems. They sleep while swimming underwater and come to the surface to breathe air.

Whales float on the surface of the ocean in small groups including their calves and other adult whales. They have basically two known methods of sleeping. Firstly, they may rest silently in water bodies, vertically or horizontally, or they may sleep while swimming in close range with other whales.

How do whales breathe when they sleep?

Whales and dolphins are breathing mammals, similar to how humans breathe. So whales are known as conscious breathers.

A whale has this unique ability to stay alert and make sure that its blowhole is on the surface of the water, helping it to breathe. Sleeping whales must keep half of their brain active and one eye open to trigger each breath when reaching the surface of the ocean while swimming with the group.

The whale's respiratory system is very different from a human's as we are unconscious breathers and have an involuntary respiratory system.

Large cetaceans like sperm whales have the ability to hold their breath for a long time. This species of whale are known for sleeping in a stationary position underwater along with its pod group.

A Baby Humpback Whale Plays Near the Surface.

How do whales sleep without drowning?

Marine mammals, like whales and dolphins, have also adapted to the method of sleeping with one eye open and half of the brain sleeping. The awake half of the brain reminds a whale to breathe on reaching the ocean surface when floating with pod members of the same species.

Whales have immense control over their blowholes so that they can breathe air and avoid drowning. They can intake more oxygen with each breath as their lungs are large-sized and can hold their breath for long enough inside water bodies.

These mammals can tolerate a high amount of carbon dioxide. Their brain only alerts them when the carbon dioxide is much more than humans can even tolerate. Moreover, with each inhalation and exhalation, they exchange more air.

Even the red blood cells in their body carry oxygen. All these factors prevent whales from drowning while they sleep.

How long do whales sleep?

Different species of whales have different time periods of sleep. Whales and dolphins have the same sleeping and resting process.

According to reports, some dolphins spend almost 33% of the day sleeping that is seven to eight hours. Large sperm whales spend only soend 7% of their day sleeping.

Humpback whales do not sleep underwater, rather they are often found resting and sleeping on the surface of the ocean. Humpback whales can sleep no more than 30 minutes. If their body remains inactive for a longer period, this may lower their body temperature.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for Have you ever wondered how do whales sleep?

Curious facts for kids then why not take a look at Do you know about biggest animals in the world? Cool animal facts, or Can dogs have salt? Know if salt is worth to feed your dog!

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Written by Ayan Banerjee

Bachelor of Science specializing in Nautical Science

Ayan Banerjee picture

Ayan BanerjeeBachelor of Science specializing in Nautical Science

Thanks to his degree in nautical science from T.S. Chanakya, IMU Navi Mumbai Campus, Ayan excels at producing high-quality content across a range of genres, with a strong foundation in technical writing. Ayan's contributions as an esteemed member of the editorial board of The Indian Cadet magazine and a valued member of the Chanakya Literary Committee showcase his writing skills. In his free time, Ayan stays active through sports such as badminton, table tennis, trekking, and running marathons. His passion for travel and music also inspire his writing, providing valuable insights.

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Fact-checked by Nishtha Dixit

Bachelor of Arts specializing in English Literature

Nishtha Dixit picture

Nishtha DixitBachelor of Arts specializing in English Literature

Nishtha is an experienced SEO writer and editor, with a passion for writing and self-expression. She is currently pursuing an undergraduate major in Literature and Communication and a minor in Political Science from the University of Delhi. Nishtha has completed a certificate master course in English from the British Council and has been appointed as the editor for the bi-monthly magazine of the University of Delhi.

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