Speaker 1: Welcome to brain Stuff, a production of iHeartRadio. Hey brain Stuff.
Speaker 1: I'm Lauren Vogelebomb, and this is a classic episode from
Speaker 1: the Vault. Today's classic has to do with whales. They
Speaker 1: are seemingly impossibly bigger than any of their cousins that
Speaker 1: live on land for a few good reasons. But given those,
Speaker 1: why aren't they even bigger? Hey brain stuff? Lauren Voglebomb. Here.
Speaker 1: If you've ever been whale watching, visited a large aquarium,
Speaker 1: or even seen the skeleton of a whale in a
Speaker 1: museum of natural history, you know the majestic massiveness of
Speaker 1: these aquatic mammals. The largest mammal to have ever lived
Speaker 1: on Earth in the history of the planet is not
Speaker 1: some prehistoric monstrosity. It's actually the blue whale, and is
Speaker 1: alive right now swimming around in our oceans. Whales range
Speaker 1: in size from the massive blue whales, which can grow
Speaker 1: to more than ninety feet that's twenty seven meters in length,
Speaker 1: to the relatively tiny pigmy sperm whales, which measure a
Speaker 1: measly ten feet or three meters in length. But with
Speaker 1: all that ocean to swim around in, why aren't whales
Speaker 1: even bigger? It's not like they have to support their
Speaker 1: big bodies on legs and walk around. For that matter, though,
Speaker 1: why aren't they smaller? Both answers have to do with
Speaker 1: food and heat. At least that's what researchers at Stanford
Speaker 1: University found when they compiled the body mass data for
Speaker 1: nearly four thousand living whales and three thousand fossilized species.
Speaker 1: Their analysis determined that aquatic mammals actually face more size
Speaker 1: constraints than their counterparts on land. The study authors determined
Speaker 1: that there are two main factors why whales are big
Speaker 1: but not bigger, heat loss and metabolism. Oceans can be
Speaker 1: pretty cold places to live, and whales, while very intelligent,
Speaker 1: don't really have the aquatic equivalent to thermal underwear. So
Speaker 1: because they're warm blooded mammals, they have to be large
Speaker 1: enough to keep from losing too much body heat to
Speaker 1: the surrounding water thermoregulation. Then it keeps whales from being
Speaker 1: the size of, say dogs. Study co author Jonathan Payne,
Speaker 1: a professor of geological sciences at Stanford School of Earth,
Speaker 1: Energy and Environmental Sciences, explained in a pressed statement, when
Speaker 1: you're very small, you lose heat back into the water
Speaker 1: so fast there's no way to eat enough food to
Speaker 1: keep up. And speaking of eating, whales have to do
Speaker 1: it a lot. Like all mammals, they convert that food
Speaker 1: into energy for swimming, growing, and doing other whale like things.
Speaker 1: That's the metabolic system at work. But the researchers suggest
Speaker 1: that the metabolism of whales only gets faster as they
Speaker 1: get bigger, and so they can only get so large.
Speaker 1: Another study co author, Craig McLain of the Louisiana University's
Speaker 1: Marine Consortium, explained it this way. Basically, animals are machines
Speaker 1: that require energy to operate. This need for energy places
Speaker 1: hard limits on what animals can do and how big
Speaker 1: they can be. So it boils down to how much
Speaker 1: which whales can eat versus their metabolic rate that keeps
Speaker 1: whales from getting infinitely large. But how do those massive
Speaker 1: blue whales get so massive? They have bay lean instead
Speaker 1: of teeth and strain their food a little shrimp like
Speaker 1: creatures called krill instead of chewing it. Krill are only
Speaker 1: a few centimeters long, but they really add up. Every
Speaker 1: day a blue whale eats about eight thousand pounds. That's
Speaker 1: over three thousand, six hundred kilos of krill so blue
Speaker 1: whales are not only the largest whales in the ocean,
Speaker 1: they're also the most efficient eaters of all. Today's episode
Speaker 1: is based on the article why are Whales so Big?
Speaker 1: On HowStuffWorks dot com written by Kristin Halgeisler. Brainstuff is
Speaker 1: production of iHeartRadio in partnership with how stuffworks dot Com
Speaker 1: and is produced by Tyler Klang. The four more podcasts
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