Free The Flight of the Iguana by David Quammen Page A

spaced just far enough from each other—as well as from the nectar glands that attract an insect’s attention—that a small insect cannot bump any two in close succession.
    The second method of measuring was discovered by Charles Darwin himself. He had noticed an odd fact about how the flytrap closes: that the closing movement occurs in two discrete phases. Upon triggering, the lobes swing together quickly (in less than half a second) to a position where the long spines have crossed but the lobe edges haven’t quite met, leaving a row of narrow, short gaps like the spaces between bars in a jail window. For the lobes to close completely, sealing off that row of gaps, takes another half hour. Why the hesitation? wondered Darwin.
    He guessed that the Venus’s flytrap was saving itself the trouble of digesting insignificant meals. “Now it would manifestly be a great disadvantage to the plant,” he wrote in Insectivorous Plants, “to waste many days in remaining clasped over a minute insect, and several additional days or weeks in afterwards recovering its sensitivity; inasmuch as a minute insect would afford but little nutriment. It would be far better for the plant to wait for a time until a moderately large insect was captured, and to allow all the little ones to escape; and this advantage is secured by the slowly intercrossing marginal spikes, which act like the large meshes of a fishing-net, allowing the small and useless fry to escape.” So the Venus’s flytrap, terror of large insects, is benignly indifferent to little ones.
    The most basic question remains: Why do they eat meat?
    Not only the Venus’s flytrap but also the sundews, the pitcher plants, and a still more elaborate genus of animal-trapping plants called the bladderworts—why do these species share a hunger for fresh flesh? Why must they feast on animal protein while other species of plant are content with sunshine, water, air, and a bit of decent soil? It seems not only presumptuous but greedy.
    The truth is exactly opposite. Carnivorous plants have been driven to this extremity not by boldness and gluttony, but by shyness and starvation.
    In the matter of habitat, evolution has awarded them hind tit. But like a determined runt that will grow into a proud hog, they make the best of it. They have developed strategies for collecting animal protein because, in the nutrient-poor habitats to which they are exiled, on soils so inhospitable that few other plants deign to invade, without some dietary supplement they could scarcely survive.
    The floating islands of peat in the Okefenokee Swamp are a representative outpost, supporting carnivorous plants of three different genera (sundews, bladderworts, pitcher plants) within little more than a canoe’s length of one another. The Pine Barrens of New Jersey can claim the same distinction. What these spots have in common with that soggy meadow in Norfolk, where F. W. Oliver saw a million well-fed sundews, is a critical shortage of the basic soil nutrients (like nitrogen and phosphorus) that most flowering plants require. One study has shown that the average patch of bog inhabited by sundews has twenty-seven times less nitrogen than the average patch of pine forest. Around the world, habitats of carnivorous species tend to fit the same pattern—plenty of water, plenty of sun, terrible soil. These are unpromising corners of real estate where, if sundews or pitcher plants weren’t growing, almost nothing else would be.
    Look at it this way: Meat-eating is the last resort of the shy, uncompetitive plant. Those carnivorous species have removedthemselves evolutionarily from the ruthless competition of the thicket, the forest, from all those fecund and clamorous places where plants flourish in wild vigor and variety, battling each other upon nutritious substrata for position and water and sunlight. The Venus’s flytrap and those few others have taken a more gentle