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Comparing Sperm Whales To Sperm: A Swimming Contest

Comparing Sperm Whales To Sperm: A Swimming Contest
Brad Purnell / YouTube

If you’re a big, big whale with a gigantic tail swimming through water, nothing gets in your way, not the water, not the other fish, not nothin’. You are so much bigger than the water molecules around you, you move through the sea the way humans move through the air on a calm day — you just go. Whales, I imagine, don’t think much about water.

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Brad Purnell / YouTube

But now, imagine yourself smaller. Much, much, much smaller. Instead of a sperm whale, let’s make you, say — a human sperm, a teeny little critter with hardly any mass, and a very skinny, beating tail. All of a sudden you are much closer to the size of the water molecules around you.


Now that you’re little, getting through water is a huge headache. You are wedged in among equal sized H2O thingies that slow you way, way down. A human sperm in water is like a car in an enormous traffic jam — barely able to move.

So how do the littlest things in life — sperm, bacteria, pond scum — get where they need to go? How to they find food? Cows don’t sit in meadows waiting for grass to grow next to their mouths …

No, little things are cleverer than that. Much, much cleverer, as you will see in this video, elegantly illustrated by Brad Purnell, narrated by Addison Anderson and thought up by Aatish Bhatia, here’s how they do it.

I guess of all the moving strategies I’ve ever encountered, this one — used by a little Broadway billboard-ish critter that dazzles trills of rainbow colored light in the shallow ocean — is the craziest. It uses the same strategies Brad and Aatish describe … but it seems to think it’s a Rockette at Radio City Music Hall.

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Gregory G. Dimijian / Science Source

And I wrote about it here.

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Robert Krulwich works on radio, podcasts, video, the blogosphere. He has been called "the most inventive network reporter in television" by TV Guide.

Krulwich is the co-host of WNYC's Radiolab, a radio/podcast series distributed nationally by NPR that explores new developments in science for people who are curious but not usually drawn to science shows. Radiolab won a Peabody Award in 2011.

His specialty is explaining complex subjects, science, technology, economics, in a style that is clear, compelling and entertaining. On television he has explored the structure of DNA using a banana; on radio he created an Italian opera, "Ratto Interesso" to explain how the Federal Reserve regulates interest rates; he has pioneered the use of new animation on ABC's Nightline and World News Tonight.

For 22 years, Krulwich was a science, economics, general assignment and foreign correspondent at ABC and CBS News.

He won Emmy awards for a cultural history of the Barbie doll, for a Frontline investigation of computers and privacy, a George Polk and Emmy for a look at the Savings & Loan bailout online advertising and the 2010 Essay Prize from the Iowa Writers' Workshop.

Krulwich earned a Bachelor of Arts degree in history from Oberlin College and a law degree from Columbia University.

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