Lee Gaillard, Philadelphia, Pennsylvania

Upon sensing danger, the bombardier beetle raises its rear end and fires off a few well-aimed rounds of chemical gas accompanied by audible pops and smoky puffs. Its artillery, a foul-smelling spray of caustic benzoquinones, explodes from its body at a blistering 212 degrees Fahrenheit--potent enough to cow most antagonists (including early naturalists, who chronicled the pain of collecting these mini panzers by hand). The repellent beetlejuice is a mixture of hydrogen peroxide and hydroquinones, which are stored together in one gland, and various enzymes contained in a second gland, which doubles as an internal-combustion chamber. In sum and substance: To disturb a bombardier is to unleash an exothermic chain of events that typically ends in grief. Chemical ecologist Thomas Eisner, a leading bombardier expert at Cornell University, contends that the insect's strategy would be unworkable for generating energy on a human scale, in part because of the difficulty and expense of storing the compounds. "You'd need beetles the size of Saint Bernards," he says.  As an alternative, consider humorist Dave Barry's proposition: putting this scrappy little bug to work as America's Official National Insect.

Do birds actually flap their wings straight up and down?

Neil O'Brian, Buffalo, New York

To fly, birds must overcome the force of gravity. While entire books have been written on this subject, birds accomplish this primarily by wing flapping, which, in aerodynamic terms, provides the thrust and much of the lift necessary to propel them through the sky. The basic motion is not straight up and down, however. Instead, the tip of the wing glides forward and downward on the downstroke, then twists at the bottom and goes upward and backward on the upstroke; it then curves again at the high point of the stroke to make the next downsweep. In effect, says biologist Ken Dial, director of the University of Montana's Flight Laboratory, birds' wings rotate as if "they're doing the breaststroke through the air." As a general rule, the smaller the bird, the more it needs to jiggle its wings to stay airborne. Ruby-throated hummingbirds, weighing less than a penny, flap at a dizzying 70 strokes per second. Golden eagles, at about 10 pounds, beat their wings but once a second. Knowledge of the dynamics of wing motion began to emerge in the late 19th century, when photographers launched the frame-by-frame study of kinematics.
Today high-speed, X-ray video images taken in wind tunnels reveal further secrets about these perfectly engineered flying machines. In navigating the firmament, it is now known, the thousands of species in the class Aves have evolved an extraordinary range of specialized modes of flight, with their flexible wings able to perform aerial feats unequaled by the mere earthbound. 

How does a chameleon change color? 

Maura Jenkins, Dearborn, Michigan
Nature's quintessential masters of disguise can go from cryptic olive to blazing Technicolor in less than 60 seconds-less time than it takes most people to put on their undergarments in the morning. Contrary to popular belief, true chameleons don't use their kaleidoscopic powers simply to blend in with their surroundings, say, by turning mottled brown when they're on a tree trunk or bright green while they're languishing on a leafy bower. The 130-odd species of the hamaeleonidae family are equipped with special pigment-bearing skin cells known as chromatophores. Like different-colored balloons, these cells inflate and deflate according to circumstances.  They are rigged to the animal's nervous system, which pretty much directs the whole show, although other factors, including light, humidity, and temperature, also come into play. Essentially, a chameleon is like a breathing mood ring, broadcasting its emotions in living color. Anger, fear, and excitement register in vivid displays that can dazzle mates, intimidate rivals, or deflect predators. Their chromatic endowments also make them desirable pets. Each year tens of thousands of wild chameleons are imported into the United States. They often die in captivity. Spread the word: Buy only captive-bred animals. For more information, call the Chameleon Information Network (858-484-2669).

By Carolyn Shea 

Illustrations by Jonathan Carlson
www.theispot.com/artist/jcarlson

Baffled by Nature?  Ask Audubon!