The Wild File


Q) Can dolphins and whales breathe through their mouths?

James B. Moon, Steamboat Springs, Colorado

A) NO, BECAUSE there's not a direct connection between a cetacean's mouth and its respiratory system. The airways of these mammals run in a straight line from the blowhole—the top-of-the-head opening that allows air to move in and out—to a pair of nasal cavities called nares and on to the larynx, the trachea, and the lungs. Unlike our own piping, this is a closed system, with rare exceptions. San Diego marine veterinarian Sam Ridgway says some cetaceans can relax the sphincter that holds the larynx in place and dislodge it, allowing air to move through the mouth and down the trachea. "It's unusual," he says, "but I have seen playful dolphins disconnect the larynx so they can blow bubbles." This anatomical quirk occurs only in toothed whales—including the sperm whale, narwhal, orca, and porpoise—and it helps explain an old maritime mystery. Back in the days when whalers hunted sperm whales, they often reported seeing fish fly through the air when the leviathans surfaced. We now know what's happening: A fish destined for the whale's gullet can sometimes jar its captor's larynx free and wriggle into the trachea and up the nasal passage. And what would you do if you had a herring in your nostril? Thar she blows!

Q) Why is there a "hole" in the Continental Divide in Wyoming, and where does rain that falls there end up?
Dean Land, Portland, Oregon

A) WHEN THE Continental Divide—the spine of North and South America, which separates rivers that ultimately flow to the Atlantic from those flowing to the Pacific—reaches southern Wyoming, it splits in two and encircles a 4,000-square-mile depression called the Great Divide Basin. According to Arthur Snoke, a geology professor at the University of Wyoming in Laramie, the basin was formed starting around 65 million years ago, when the faulting and folding that created the eastern Rockies caused an uplift on all sides of this piece of land, cutting it off from the watershed. Thus, all the rain that falls in the basin, which on average is 500 feet lower than the ridges surrounding it, either ends up in the basin's groundwater or evaporates. This isn't the only unusual water feature on the divide. Just south of Yellowstone National Park, a stream on the western side of the divide called North Two Ocean Creek becomes the victim of "stream piracy." Atlantic Creek, on the eastern side of the same ridge, is slowly extending its gully uphill through erosion, and it now, in effect, crosses the divide and captures some of Two Ocean Creek, while the rest of Two Ocean continues west, under the moniker Pacific Creek. Which makes this point, the Parting of the Waters landmark, the only place in this country where you can swim in water that's bound for two seas.

Q) With so many species dying off due to habitat destruction, are new species being born?
Hannah Shepard, Bralorne, British Columbia

A) "EVOLUTION NEVER stops," says Eric Dinerstein, a biologist with the World Wildlife Fund. Even as some 30,000 species disappear each year (counting only those visible to the naked eye), new ones are always in the works. But that's the only good news. Since a new species takes, say, 100,000 years to emerge, scientists guess that the world's rate of extinction is now a million times greater than its rate of speciation. The bulk of this loss of life can be blamed on human encroachment. In the 20th century, about 250,000 species went missing, and as deforestation continues at an exponential clip, scientists fear that 25 to 50 percent of the ten million species among us could be gone in 100 years. Finally, as ecologically important creatures are getting the ax, just what sorts of new species are coming onto the scene? Mostly viruses, and a new mosquito that's said to be breeding in the London Underground.

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