Elephant seal resting on a rocky beach with a distant shoreline in the background.

Imagine this scenario: You’re going for a jog outside, but seeing some snow on the ground, you decide to put on a thermal long-sleeve shirt underneath your sweatshirt. Right as you step out the door, you sure are glad you added that extra layer. After a few minutes into your jog, you notice you’re breathing heavy and your heart is beating faster (…especially if you’re out of shape). Your skin might get red, feel hot and flushed, and after a little while, you’ll probably also start sweating. These physiological responses keep your body fueled with oxygen during your aerobic workout while also preventing you from overheating. But you still start to feel slightly uncomfortably warm.

What do you do? Easy enough, just take off the extra layer!

Now imagine that ‘extra layer’ came in the form of thick blubber as it does for marine mammals. How do marine mammals cope with variable thermoregulatory demands—conserving heat while diving to cold depths but dissipating any excess heat when actively swimming? Whales, dolphins, seals, and sea lions are endothermic mammals, just like we are, and have to regulate their body temperature. But, they cannot just easily take off their blubber layer like we do with our clothes.

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