The Flight of the Iguana (8 page)

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The Cloudsley-Thompson scenario and that last statistic, though, may both be unduly alarming.
C. sculpturatus
is quite common in Arizona, and many people are stung by it without suffering any harrowing effects. One of those victims, Steve Prchal of the Arizona-Sonora Desert Museum near Tucson, describes the experience this way: “Take a sharp needle and jab it into your hand. Hold a match or a lighter to it for a couple
hours. Then add the needles-and-pins sensation you have when a foot falls asleep. That's what a bark scorpion sting feels like.” Evidently the reaction can range anywhere from modest discomfort to horribleawful death, depending upon the body size and general health of the person stung, as well as other obscure factors, including luck. Best to steer clear of scorpion habitat, then, when you feel especially frail or unlucky.

Steve Prchal got his sting during a family camping trip, five minutes after having warned the other family members to be careful of scorpions. He reached for a boat cushion that had been drying on top of a bush. Whammo. That pattern seems to be typical. But considering both the number of scorpions and the number of people at large in the state of Arizona, sting incidents don't happen nearly so often as they might. What makes scorpions a threat to humanity is no special bellicosity on the part of the scorpions but the fact that, because of their shy inconspicuousness, you don't see them until it's too late.

They hide during the day, under bark or in rocky crevices or burrowed down into the sand, emerging nocturnally to hunt. They are discreet. If you have ever lain down in a sleeping bag on the warm Arizona earth, you have probably had a closer encounter with these creatures than you realized. Still, on visual evidence you might well conclude that they aren't really there. Vivid remedy for any such happy illusion can be derived, it turns out, from another strange scorpion attribute: Under ultraviolet illumination, they glow in the dark. They fluoresce. Shine a black-light beam on them and (due to photochemical properties of the scorpion integument about which little seems to be known) they reflect back an eerie greenish-blue radiance. Like a zodiac image in garish neon except that the animal, and the sting, are quite real.

Steve Prchal designed the live-scorpion exhibits at the Desert Museum. He tells of going out on collecting trips, sometimes to a hilly area cut by a certain gorgeous little hidden canyon, down
near the Mexican border west of Nogales. Like many collectors, he went at night and used an ultraviolet flashlight, shining his invisible beam along the steep walls of a wash. “It was like stars,” Prchal says. “It would scare the hell out of you to see how many you'd be sleeping with if you camped there.” He didn't camp there, because he was too smart. I wasn't, when I lived in those parts, so I did. Saw not a single scorpion. Carried no ultraviolet flashlight. Padded around on the gravel after dark in my stocking feet. Got an excellent night's sleep. I believe that the phrase Thurber used, in a similar application, was “living in a fool's paradise.”

Curious about how others have fared among those great scorpion multitudes of the Arizona outback, I decided to consult a couple of postdoctoral desert rats. First I called one Doug Peacock, an eminent monkey-wrench environmentalist and authority on the wild behavior of grizzly bears and humans. Peacock, in his many years of crashing around the desert outback, has collected three scorpion stings, and he remembers them all rather vividly. The first time was the worst. He was tucked into his sleeping bag, somewhere out on the Cabeza Prieta wildlife refuge, and in the middle of the night he chanced to roll over, flopping his arm out blindly onto the sand. Whammo. This one may or may not have been
C. sculpturatus
—he didn't get a look at the perpetrator—but the localized pain was ferocious and he went through a few hours of bad headache, nausea, and fever. The third time, out scouting for billboards to chain-saw or bridges to dynamite, he sat down in a clearing and laid his hand back for support—right on a scorpion, which went off like a mousetrap. Either because it was a less toxic species, or because by now Doug was growing immunized, or for some other unplumbable reason, in this case the effects were no worse than those from a bee sting. The second time was perhaps the most interesting. Again on a solo ramble across the Cabeza Prieta, he was sitting up late to read
Moby Dick
by the light of his campfire. He set the book down, tossed a
few sticks on the fire, watched the sparks rise into black eternity, picked the book up, leaned back comfortably on an elbow, and whammo. In his annoyance he pummeled this one to death—in fact, past all chance of taxonomic identification—but a reasonable bet makes it
C. sculpturatus.

I also talked with Ed Abbey, whose credentials to speak in any matter of deserts or ornery critters are unequaled. Amazingly, Abbey has only been scorpion-stung once, and that time while sitting quietly on a couch in a trailer house, late one night about a dozen years ago. He was barefoot. He was reading
Gravity's Rainbow.
He didn't notice the scorpion that had come crawling peacefully up. He lifted one foot and set it down again, whammo, but Ed was so engrossed in Pynchon's novel that all he recalls is tromping the scorpion to death with his stung foot, then quickly fetching a bucket of ice water, jamming the foot into it, and continuing to read. Yes, his assailant seemed to have been that species they call the bark scorpion. Yes, he had some sharp pain at the site, definitely, but nothing much more. On the whole, says Ed, it wasn't nearly so traumatic as the time a tiny insect, species unidentified, crawled deep into his ear and refused to come out.

There are several morals to be drawn. First and most obviously, heavy reading causes scorpion sting. Second, a person is safer while remaining stationary than in making even the most innocent movement—and safer still if the person remains stationary somewhere outside the borders of Arizona. And a third point to note is that the obliviousness seems to be mutual: They don't see a human hand or foot coming, those bumbling scorpions, until it's too late. Otherwise they would surely, like us, prefer to avoid the whole experience.

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They don't see us coming because they don't see much of anything. Ironically, despite their superabundance of eyes, most scorpions seem to be almost hopelessly blind. Scientists who study scorpion biology generally mention this handicap (“The
eyes are too crude to be of much assistance. . . . The eyesight seems to be of secondary importance. . . . Scorpions have poor eyesight”), which is so pronounced, evidently, that it has been a mystery how scorpions could ever find their way to a meal. Stumbling around blindly out there in the desert, bumping into rocks and each other and Doug Peacock, the poor things should have long since starved to death and lapsed into extinction. Just lately, though, the mystery seems to have been solved.

In a recent issue of
Scientific American,
Philip H. Brownell has presented impressive experimental evidence for a new theory of how scorpions perceive the presence of food or danger.

They see with their feet.

More precisely, they rely on pressure-sensing organs near the ends of each of their eight walking legs to detect subtle shock waves that propagate outward, even through sand, when another creature passes by on the desert floor. According to Brownell, the scorpion orients itself toward the focus of any such disturbance by gauging the minuscule differences in the times at which the shock wave reaches each of its eight spraddled legs. Spaced apart, those legs serve as stereoscopic receptors. Take away the sensory input from one or two pairs of legs, or from all four legs along one side of the body, and the scorpion becomes confused. Disoriented. Like a human with only one good ear, and therefore no sense of auditory direction—or with only one good eye, and therefore no sense of depth. Take away all the input from those leg organs, and the scorpion is functionally blind.

They see with their feet. No wonder they need all eight. Okay, this I can accept. But I'm still uneasy about all those sparkling eyes, which seem to serve no purpose except sheer decorative vanity. They don't walk with them. They don't depend upon them for vision. Couldn't they be satisfied with just five or six?

The Well-Kept Secret of Carnivorous Plants

Plants that eat animals are looked at, by us animals, askance.

They are perceived as grotesque, menacing, unnatural, horrific—or sometimes just delightfully sinister, in the campy spirit of Vincent Price. Above all, they are seen as aggressive beyond their proper station in life. Their presumptuousness seems Promethean, with us for once on the side of the gods. Nature knows them in 450 different species, and the human imagination has been compelled to invent more. Those imaginary varieties grow to huge elephant-ear sizes and flourish in dense Hollywood jungles, feigning innocence among the other foliage, waiting to clamp closed on a cockatoo or a chimp. Minor-key organ chord while the chimp preens, oblivious, and the big ugly plant drools its caustic juices. Most recently we have Audrey II, the ravenous cabbage of
The Little Shop of Horrors.
But even Audrey is the epigone of an older model: On the island of Madagascar, according to legend, there lived a man-eating tree.

Some of the genuine botanical realities can be made to seem, on their own modest scale, almost as chilling. The American pitcher plants feed not just on insects but also on small lizards and frogs. A large pitcher plant called
Nepenthes,
native to Borneo, has been caught in the act of digesting mice. The biggest of
the sundews, an Australian species named
Drosera gigantea,
grows into a three-foot-high bush of sticky, grabby paws. Then there's the gaping red maw of the Venus's flytrap, armed along each lip with a row of needle-like spines that were once thought to be capable of impaling victims. My own favorite bit of lore, though, involves the collective accomplishment of a whole field full of common British sundews.

On August 4, 1911, in the county of Norfolk on the east coast of England, a scientist named F. W. Oliver came across a two-acre meadow carpeted solid with sundews. These pretty little plants consist of a rosette of club-shaped leaves radiating from a central stem, each leaf covered with small tentacles at the end of which is a knobby gland, each gland wrapped in a drop of glistening mucilage. In the meadow when Oliver found it, every individual plant had recently captured between four and seven specimens of
Pieris rapae,
a small white butterfly. Evidently the butterflies were a migrating flock that had flown across from the Continent, settling on this flowery field for a rest and a snack. They had chosen badly, and the flock would be going no farther. The sundews were in the act of digesting them.

By Oliver's estimate, that field of plants had just eaten six million butterflies.

Now the
Pieris rapae
butterfly, in its larval stage, is itself a notoriously voracious plant-eater. For six million of them to gobble away two acres of vegetables would be a routine agricultural annoyance. So why should it seem more macabre when the tables are turned?

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Evolutionary biologists have been intrigued by the varieties of flesh-eating flora ever since Charles Darwin, who wrote an entire book titled
Insectivorous Plants.
Darwin himself had gotten interested during the summer of 1860, just after publication of
The Origin of Species,
when (on a heath in Sussex) he stumbled across a large insect-kill like the one later described by Oliver. The perpetrator
in Darwin's case was also the common sundew,
Drosera rotundifolia,
and because that species was locally plentiful and could be cultivated at his home for use in experiments,
D. rotundifolia
became the main focus of Darwin's book. “I care more about
Drosera
than [about] the origin of all the species in the world,” he confessed intemperately in one letter. He also harbored a special fond fascination for the Venus's flytrap, which is a purely American species that Darwin had never seen in the wild, and which he called “the most wonderful plant in the world.” Darwin begged samples of the flytrap from his American colleagues, tried to raise the species in his own greenhouse, and had to lament that “I cannot make the little creature grow well.”

He needn't have been hard on himself about that, because the Venus's flytrap is drastically finicky about its habitat. There is only one species, and that species confines itself to only one native range: a narrow strip of coastal plain in the Carolinas. The flytrap is so sensitive to its own habitat requirements that, even within such a small range, it can survive only in very particular types of terrain. More about this choosiness in a minute.

Despite its rarity, the Venus's flytrap is the most famous of carnivorous plants, and we are all roughly familiar (we think) with its general anatomy and behavior. Each leaf is modified to the shape of a leg-hold trap, two semicircular lobes on a hinge, cocked open invitingly but ready to slam shut the instant a trigger is tripped. Right? Along the rim of each lobe protrude those needle-like spines. Maybe they can't stab an escaping fly, as once thought, but they certainly add to the aura of implacable malice. Right? The inner surfaces of the lobes are cobbled with tiny liquid-filled glands, some of which show a mysterious red coloring, some of which exude a clear nectar. An insect is attracted by the color and smell, lands on or crawls into the open trap, and then—the heart-sinking snap. The insect's demise is ugly, remorseless, and sudden. Right?