By: Lili Wilson

As a naturalist on a whale watching vessel, I spend serious quality time with whales, and almost as much time answering questions about whales. These charismatic megafauna attract legions of tourists and locals who want learn about a day in the life of a whale. The following are some questions that I answer almost daily with some added fun facts.

Orca in the Salish Sea. Photo credit: Lili Wilson

1. How do whales sleep?

Just like us, whales require a certain amount of brain rest. Unlike us, whales are conscious breathers, which means they need to actively decide to swim to the surface to breathe. Therefore, it would be highly problematic for a whale to fall completely asleep. Luckily cetaceans have conquered this challenge by always keeping (at least) half their brain awake – a concept known as unihemispheric slow wave sleep. This allows them to keep one eye open and continue to surface to breathe throughout their nap.

2. Why would whales evolve to breathe air if they live underwater?

Whales did not evolve from animals that extract oxygen from water. Life began on land around 375 million years ago. Mammalian life evolved on land 200 million year ago, and whales began evolving from those animals around 50 million years ago. The first “whales” look nothing like what we see today. Pakicetus, one of their more ancient relatives, looked like a dog with hooves, and likely spent much of its time on land. Cetaceans are most closely related to the cloven-hooved animals, and it is commonly thought that the hippopotamus is their closest living land relative. Over time, whales evolved into entirely aquatic beings while continuing to breathe air.

Humpback whale off the coast of Vancouver Island. Photo credit: Lili Wilson

3. How long can a whale dive?

The deepest a whale can dive entirely depends on the type of whale. Killer whales usually dive for 3 to 5 minutes, humpbacks are often under water for 10 to 15 minutes. The deepest and longest diving whale is known as Cuvier’s beaked whale which has been documented diving to around 3000 meters. These elusive creatures are difficult to study as they can dive for over two hours! These critters must breathe air, but also withstand the immense pressure of having several kilometers of water above their heads.

Humpback breaching. Photo credit: Lili Wilson

4. Why do they jump?

Many people want to know why some of the largest animals on the planet would throw its entire body out of the water – and honestly, so do I. The truth is, there is no one consensus on why whales breach, but there are some hypotheses. Humpbacks are known to be particularly acrobatic and have been popular subjects due to their splashy behaviour Many people who have been lucky enough to observe jumping whales believe they are showing excitement. On the contrary, it may also be a warning that predators are in the area. Newer studies are showing that it is likely also a form of acoustic communication. When 80 thousand pounds of blubber and baleen hit the water, the sound carries for miles.  For closer range communication (outside of vocalization), they can slap the water with their tail and pectoral fins.

 Lili Wilson is a naturalist on a whale watching vessel in Victoria, B.C. In or out of work, she is usually found talking about whales to anyone who will listen. With a background in Biology and Environmental Studies, she hopes to improve the state of our oceans and motivate others to do the same. Lili is passionate about sharing the ocean world through speech, the written word, and photography. Connect with her on Instagram or on her website

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