The Wild File

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Q)Which spider makes the strongest web?

The Wild File: Outdoor Questions Answered

Brandon Culberson, Raleigh, NC

Sadly, no one has volleyed objects into the webs of the 37,000 known spider species to find this out, but when it comes to spinning strong silk, the golden orb weaver (Nephila clavipes) is thought to be the champ. According to Cheryl Hayashi, a biology professor at the University of California at Riverside, the female Nephila, whose three-foot webs are found in the Americas as far north as the Carolinas, produces dragline silk that's better at absorbing impact than steel and Kevlar—which explains why its use has been considered for the manufacture of bulletproof vests. The main obstacle: There's no efficient way to corral the cannibalistic spiders en masse, like silkworms, for the sake of extracting their precious superstring.

Q)What is the oldest river in the world?
Kent Wosepka, Hamilton, Ma

That's a tough one, because it's hard to determine whether any river today is the same river that was there ten million years ago. Given that, many scientists cite the Finke River, in central Australia, as the most ancient. Vic Baker, a paleohydrologist at the University of Arizona, in Tucson, says that while this is far from verifiable, the Finke is definitely very old. The reason: It runs in a line perpendicular to the local geological structure—in this case, a couple of mountain ranges—an indication that the river was present before the structure formed. As the mountains pushed up, the river cut deep canyons, the rimrock of which shows 400 million years of erosion. Since it can be presumed that this rock was once at river level, the river must be at least 400 million years old. Mind you, as with other "world's oldest rivers," most interest in the topic comes not from scientists but from local tourist boards. "I guess it sounds sexy," Baker speculates, "to say your town has the oldest river." Q)Why are some animals colorblind?
Jordan Paul, Simsbury, Ct

With the exception of a few weird sea creatures and nocturnal species, no animal is truly colorblind, but some don't see as many colors as we do. The difference is in the eyes' cones, neuroreceptors that pick up information from different wavelengths of light. The majority of mammals have only two kinds of cones, while most primates, including humans, have three. Why are some critters shortchanged? According to Jay Neitz, a professor of cell biology and ophthalmology at the Medical College of Wisconsin, in Milwaukee, when primitive mammals began to flourish, about 100 million years ago, they had four kinds of cones. But because dinosaurs ruled the daytime, these proto-mammals had to skulk after dark, when color is less important, so over time they lost the two types they weren't using; only later did primates evolve a third cone type. Meanwhile, most fish, birds, and reptiles still have four kinds of cones, and some butterflies, like the Japanese yellow swallowtail, have five. Compared with them, we're the ones who are colorblind.

Q)What's the difference between talus and scree?
Mike Mendonsa, federal way, Wa

These two words are often spoken in the same breath, and indeed, both are defined in the Dictionary of Geological Terms as "a heap of rock waste at the base of a cliff." An informal survey of climbers suggests that, for some, the words are interchangeable, while others feel that size matters: Scree is usually thought of as the gravel spread across a steep slope, while talus implies rocks that are fist-size, head-size, or even furniture-size. For climber-adventurer Will Gadd, the important part is whether you're going up the mountain or down: "Talus means boulders—period. Scree is the slippery stuff that, on the ascent, causes you to fall on your ass. But on the descent it's beauteous, because you can slide down it like a skier." So just remember: Scree rhymes with whee!

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