WEBVTT - BrainStuff Classics: Why Are Whales Big (But Not Bigger)?

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<v Speaker 1>Welcome to brain Stuff, a production of iHeartRadio. Hey brain Stuff.

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<v Speaker 1>I'm Lauren Vogelebomb, and this is a classic episode from

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<v Speaker 1>the Vault. Today's classic has to do with whales. They

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<v Speaker 1>are seemingly impossibly bigger than any of their cousins that

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<v Speaker 1>live on land for a few good reasons. But given those,

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<v Speaker 1>why aren't they even bigger? Hey brain stuff? Lauren Voglebomb. Here.

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<v Speaker 1>If you've ever been whale watching, visited a large aquarium,

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<v Speaker 1>or even seen the skeleton of a whale in a

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<v Speaker 1>museum of natural history, you know the majestic massiveness of

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<v Speaker 1>these aquatic mammals. The largest mammal to have ever lived

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<v Speaker 1>on Earth in the history of the planet is not

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<v Speaker 1>some prehistoric monstrosity. It's actually the blue whale, and is

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<v Speaker 1>alive right now swimming around in our oceans. Whales range

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<v Speaker 1>in size from the massive blue whales, which can grow

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<v Speaker 1>to more than ninety feet that's twenty seven meters in length,

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<v Speaker 1>to the relatively tiny pigmy sperm whales, which measure a

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<v Speaker 1>measly ten feet or three meters in length. But with

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<v Speaker 1>all that ocean to swim around in, why aren't whales

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<v Speaker 1>even bigger? It's not like they have to support their

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<v Speaker 1>big bodies on legs and walk around. For that matter, though,

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<v Speaker 1>why aren't they smaller? Both answers have to do with

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<v Speaker 1>food and heat. At least that's what researchers at Stanford

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<v Speaker 1>University found when they compiled the body mass data for

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<v Speaker 1>nearly four thousand living whales and three thousand fossilized species.

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<v Speaker 1>Their analysis determined that aquatic mammals actually face more size

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<v Speaker 1>constraints than their counterparts on land. The study authors determined

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<v Speaker 1>that there are two main factors why whales are big

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<v Speaker 1>but not bigger, heat loss and metabolism. Oceans can be

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<v Speaker 1>pretty cold places to live, and whales, while very intelligent,

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<v Speaker 1>don't really have the aquatic equivalent to thermal underwear. So

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<v Speaker 1>because they're warm blooded mammals, they have to be large

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<v Speaker 1>enough to keep from losing too much body heat to

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<v Speaker 1>the surrounding water thermoregulation. Then it keeps whales from being

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<v Speaker 1>the size of, say dogs. Study co author Jonathan Payne,

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<v Speaker 1>a professor of geological sciences at Stanford School of Earth,

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<v Speaker 1>Energy and Environmental Sciences, explained in a pressed statement, when

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<v Speaker 1>you're very small, you lose heat back into the water

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<v Speaker 1>so fast there's no way to eat enough food to

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<v Speaker 1>keep up. And speaking of eating, whales have to do

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<v Speaker 1>it a lot. Like all mammals, they convert that food

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<v Speaker 1>into energy for swimming, growing, and doing other whale like things.

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<v Speaker 1>That's the metabolic system at work. But the researchers suggest

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<v Speaker 1>that the metabolism of whales only gets faster as they

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<v Speaker 1>get bigger, and so they can only get so large.

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<v Speaker 1>Another study co author, Craig McLain of the Louisiana University's

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<v Speaker 1>Marine Consortium, explained it this way. Basically, animals are machines

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<v Speaker 1>that require energy to operate. This need for energy places

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<v Speaker 1>hard limits on what animals can do and how big

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<v Speaker 1>they can be. So it boils down to how much

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<v Speaker 1>which whales can eat versus their metabolic rate that keeps

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<v Speaker 1>whales from getting infinitely large. But how do those massive

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<v Speaker 1>blue whales get so massive? They have bay lean instead

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<v Speaker 1>of teeth and strain their food a little shrimp like

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<v Speaker 1>creatures called krill instead of chewing it. Krill are only

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<v Speaker 1>a few centimeters long, but they really add up. Every

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<v Speaker 1>day a blue whale eats about eight thousand pounds. That's

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<v Speaker 1>over three thousand, six hundred kilos of krill so blue

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<v Speaker 1>whales are not only the largest whales in the ocean,

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<v Speaker 1>they're also the most efficient eaters of all. Today's episode

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<v Speaker 1>is based on the article why are Whales so Big?

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<v Speaker 1>On HowStuffWorks dot com written by Kristin Halgeisler. Brainstuff is

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<v Speaker 1>production of iHeartRadio in partnership with how stuffworks dot Com

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<v Speaker 1>and is produced by Tyler Klang. The four more podcasts

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