Jerome Shea December 6, 2009 Weekend Wonk
Ever notice that some animals seem to have real trouble following the script? Take your penguin, for example. As a bird he is a disgrace (I’m sorry, but it’s time somebody said so and if it has to be me, well there you are then). Your penguin could pass muster as a portly butler in a whodunit, but where he really shines—if you have ever seen him gracefully cavorting under water—is as a fish. What’s—as they say—with that? And if penguins insist on behaving like fish, at least they do a better job of it than the ostrich, another bird with suspect credentials and ugly into the bargain. Speaking of fish, I learned just yesterday that some of them are warm-blooded. Now that’s plain wrong, and how am I going to break that news to the goldfish in my backyard pond, gliding numbly under the ice, semi-comatose till next May? Then we have fish who, tiring of one pond, can trundle awkwardly to a neighboring one. “Fish gotta swim and birds gotta fly”? Don’t bet on it.
And don’t even start with me on marsupials.
But I come today to talk about whales, another major disappointment. We all know—Aristotle noticed and noted the fact over two millennia ago—that whales and other cetaceans are not fish, but mammals. They are warm-blooded, birth their calves live, and produce milk to nurse them. They even have vestigial body hair in the form of whiskers around the snout, the skeletal structure inside their (front) flippers is clearly mammalian (they lost their hind legs, and flippers, millions of years ago), and they have horizontal, not vertical, tails.
We all know that life began about a gazillion years ago in the primordial ocean, a sort of amniotic fluid vaster than we can imagine, the Great Womb of Life. We know, too, that some life forms elected to stay there, and I am sure that sharks and salmon and whatnot had their good reasons. I have no quarrel with our finny brethren. My goldfish are much more attractive gliding under water in the pond that I dug for them than stomping around in the compost pile looking for food. More power to them, I say.
But who can forget that awe-inspiring parade in your old biology textbook where the first restless marine critter seeks a better life for herself. She develops a primitive lung, her fins get more and more stumpy, and there she is, ambling awkwardly up the beach. (You go, girl!) In a trice, geologically speaking, she is transmogrified into a lizard, a dinosaur, a lemur, a proto-ape, a homo erectus, and—voila!—your grammar school teacher or Dolly Parton (and her husband, of course). We did it! We became mammals! And as mammals we voted overwhelmingly for the life terrestrial.
So why in the name of all that’s holy did the ancestors of the whales decide to do an about face and go back to the briny? Because that is precisely what they did. Purple mountain majesties and fruited plains just didn’t seem to do it for them: oh no, they decided to go back to the Great Womb. Slackers.
This has always fascinated me. Not just the arresting fact that they decided to return to the sea, but just what they looked like before they slowly became the whales that we know. Paleontologists think they have a pretty good candidate in the mesonychid, a creature that walked the earth back in the early Paleocene epoch. The mesonychid was about the size of a wolf, an ugly beast that you wouldn’t want to meet on a dark night. It fed on carrion and was a proto-ungulate, which is to say its claws were slowing evolving into primitive hoofs. (Going way, way back in the family tree, zoologists think that whales and hippos are pretty closely related.) Try to imagine this animal slouching silently through the dripping ferns, always hungry. Perhaps it developed a special taste for marine carrion? Perhaps an idea finally glimmered in its brain: why feed on dead scraps when, wading farther and farther into the water, you might wind up at the main buffet? Maybe that’s how it happened. Just a thought.
And if that doesn’t awe and intrigue you, consider that this inconsiderable animal evolved into, among other species, the blue whale, the largest creature that ever lived on land or sea. How did that happen, you ask? Beats me, but I am not sure that the experts agree on how it happened either. Consider first, though, that with enough time almost anything can happen, and that we are talking about more than 70 million years. Two other things come to mind. One is the buoyancy that water, especially salt water, provides. You don’t have to depend on legs to support you, so that particular design element is now irrelevant. Secondly, of the two sub-orders of whales, those with teeth and those with sheets of baleen instead, the latter are the real giants. With their ability to sieve their way through clouds of krill and schools of herring, anchovies, sardines and other small prey, they can ingest meals of truly prodigious proportions. Again, just a thought. But with those two factors in play, the sky is probably the limit.
So there are Shea’s ruminations on whales. You’re welcome.
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