Tropical Nature by Adrian Forsyth

Author:Adrian Forsyth
Language: eng
Format: epub
Publisher: Touchstone
Published: 1984-03-01T16:00:00+00:00

ARTFUL GUISES

This life’s five windows of the soul Distorts the Heavens from pole to pole And leads you to believe a lie When you see with, not thro’ the eye.

—WILLIAM BLAKE

“The Everlasting Gospel”

A naturalist’s first visit to a tropical rain forest can be both an exhilarating and disappointing experience; the richness of the vegetation may overwhelm the senses at first, but sooner or later the apparent scarcity of animal or insect life will begin to raise questions.

Although large animals may indeed be scarce in many rain forests, smaller creatures lie all around you. Many of them will probably be sitting in plain sight, but they may not be what they appear to be. The tropical rain forest is full of sophisticated visual tricks, played for high stakes by one creature against another. So don’t be deceived into thinking that animals are scarce just because you can’t see them. Wherever you go in the rain forest, unseen eyes lie hidden in the greenery.

Some of the most beautiful eyes in the tropical rain forest never see. Painted on the hind wings of many moths in rich detail are false eye spots—deep blue spheres countershaded with ebony and highlighted with shiny silver flecks. During the day these eyes lie hidden beneath the soft cover of the moth’s wings, and therein lies their value. If you poke around the forest by day with your nose close enough to a tree to smell the lichen and bark, you may find a resting silk moth. Some of these moths, which are well represented in the tropical rain forest, have wing spans as large as your hand, yet they are seldom seen because their mottled forewings, painted with blotches and streaks of brown, russet, and tan, render them anonymous on varicolored tropical tree trunks. A sleeping moth this large is a tempting curiosity and few people who spot one can resist nudging it.

Only then is the splendid artistry of the hidden eye revealed. The moth rapidly spreads its forewings, and in place of a cryptic mottled moth, shining bright eyes the size of an owl’s suddenly glare forth. Even if you know what to expect, their sudden appearance is surprising. This flashing of bright eyes has the same jolting effect on a foraging bird who might take a tentative exploratory poke at the moth. Experiments have shown that these eye spots startle hungry birds, sometimes to the point of scaring them away. But even if the bird is not frightened away, its brief double-take might be enough to give the moth an opportunity to fly off.

Insects do not stop at simple imitations of disembodied eyes. Certain sphinx moths, whose caterpillars are as large and conspicuous as small cigars, use a more radical approach. When molested, the caterpillars constrict certain muscles that magically transform their body into an excellent duplicate of the head of a small viper. The enlarged triangular head, prominent eyes, and swaying motion faithfully duplicate the appearance of the real thing. This must have at least the same impact on birds and lizards as simple eye spots.

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