An American chameleon colors expectations.
A winsome little fellow it is. Often you may find it quite by accident, in quiet repose on a chocolate-hued alder branch. Mostly brown, it lies with white tummy down, spread-eagled like a shaggy dog on a linoleum floor in the dead of summer. At other times you may see it in green--when it's restive and on the move, continually twisting its reptilian head, tiptoeing down one branch, up another, searching for prey or avoiding a larger predator's search.
What is this long-bodied, scaly, four-legged, wispy-tailed critter of fast step and saurian demeanor? It's the green anole, Anolis carolinensis--one of 3,000 species of lizards worldwide, the northernmost of 200 lizards attached to the genus Anolis, and denizen exclusively of the southeastern United States, from southern Virginia to Florida and west to eastern Texas.
Belonging to the order Squamata (which includes lizards, skinks, and snakes) and the family Iguanidae (like the iguana of The Night of the Iguana fame), the green anole is one of 115 lizard species and 50 iguanids found in North America. Other anoles--like the largehead (A. cybotes), bark (A. distichus), knight (A. equestris), and brown (A. sagrei)--are found in Hispaniola, Cuba, or the Bahamas, with subspecies on the tip of Florida.
A diurnal, arboreal species, the green anole is at home in a diversity of habitats and can be observed in fields, forests, gardens, and even hammocks. Study this reptile through a 300-millimeter zoom lens. Although it appears smooth skinned to the naked eye, through a lens its keeled scales are evident. Delicately cut and close fitting like pieces of a jigsaw puzzle, the scales are neither obvious nor overlapping as found on some other types of lizards.
Spying on Ms. Brown
The green anole's behavior and appearance aren't always easily explained through gross observation. One morning in early July, I spy a mature brown female, about 4-5 inches in total length, lying on a branch. (I identify her as a female because she lacks the mature male's prominent red dewlap.) She soon gets up and descends the alder, carefully stepping with wide-toed feet terminated by tiny claws. Before she reaches the ground, her big, rubbery toes become ensnarled in a vine. She drops off a branch, hanging upside down on the vine like a green boot camper on a rope. She disappears, except for her long tail, until that too zips away like a string of spaghetti between sucking lips.
A week later, on the same tree, what appears to be the same brown female lies on the same spot on the very same branch as before. The exact relocation suggests a homing instinct with a narrow home range for this cold-blooded vertebrate. Anole territories may range from several square feet to a circular area with a 100-foot diameter.
But what is Ms. Brown--if you may call her that--still lazing about? Is she anticipating a passing meal, like an orb weaver? Maybe she's awaiting a male--assignation amid the alders, tryst in the trees. Although anoles may mate into early fall, the females commonly lay one or two eggs every 8-14 days, over an 18-week spring/summer period. In July, then, the female may just be tired and resting up after completing some reproductive chore.
Both sexes reach sexual maturity in three months. But neither parent guards the eggs, which are laid in moist soil or leaf litter and hatch after six or seven weeks. The newly born, inch-and-a-half replicas are left to fend for themselves.
Meanwhile on the alder, Ms. Brown is engaged in not being engaged. Suddenly she sheds her indolent attitude, as she espies a green katydid on a leaf a foot above her head. When the intruder attempts a couple tentative steps on the leaf, the lizard quickly twists her head back over her shoulder, a sharp crease etching her creamy neck.
How could she detect something so silent, so seemingly inconspicuous as this katydid's tiny movements? The answer seems to lie in the lizard's acute sensitivity to sound and physical vibrations. Besides its scales and claws, a third trait distinguishes the anole from a similarly shaped and proportioned creature--the amphibious salamander. Unlike the latter, the anole bears a pair of external ear openings: small, dark holes near the back of its wedge-shaped head.
Perhaps the anole has been lying in wait for a meal after all, the alder leaves serving as platters for such smorgasbordian delights as spiders and other arthropods, including crickets, cockroaches, and flies. Immediately, the lizard breaks its repose and zips up off its lounging branch towards its green prey-to-be. How can such a laid-back critter move so rapidly, quicker than the eye can follow? Ms. Brown's big feet busily try to negotiate a leaf's edge as she franctically fights to keep from falling. But she misses the target, and recovery becomes paramount. Finally, she pulls herself atop the leaf.
Was this an emotional moment for the anole? If so, this dubbed for its ability to change color--does not turn red with chagrin, purple with rage, or blue with the blahs. Jokes aside, what's puzzling is that Ms. Brown stayed brown, although an anole's color is said to be alterable in seconds, influenced largely by the animal's emotions. The brown coloration appears during periods of rest, such as at night. But when excited or active, it displays various shades of green--from the brightest, when most agitaged, to the dullest, grayish green. Yet this anole stayed brown. Even when on the attack in the heat of the day, Ms. Brown kept her cool.
Conversions of color
The green anole is able to change its color by expanding and contracting certain skin cells, called chromatophores, which contain a black pigment. When these cells enlarge to cover other cells, the anole appears brown. When the chromatophores contract, the animal turns green or greenish. These movements are triggered and controlled by hormonal activity, such as that associated with fear of predators or excitement on encountering the opposite sex.
This saurian's color is also influenced by temperature, humidity, and the intensity of light. There is an interplay of control by optic and skin receptors to light. When the animal is exposed to cold, dry weather or bright light, its color is most often brown, while warm temperatures, high humidity, and dim light generally change the coat to green. The temperature and eye reception to light are thought to influence body color except when the anole is under stress or excited.
The green anole's reputedly rapid color-changing ability makes it the darling of pet shops and a sure attention getter for naturalists. But the American chameleon is hardly a close relative of Africa's true chameleon--that humpbacked, goggle-eyed, rough-skinned, ogrish fellow who would have had little difficulty snapping up any nearby katydid with its long, clublike tongue. Besides, it's debatable whether the green anole can deliberately flip colors like a true chameleon, that is, in order to hide from its enemies.
By mid August, I find several little anoles climbing, crawling, or scampering, as if on their own hunts. Smaller and more active than the regal Ms. Brown, they are probably young of the year, having grown rapidly after hatching in early July. They are green to varying degrees--never the bright green associated with high excitement but dark, olive green (grayish in spots), associated with mild activity. They will survive no more than two years in the wild.
The "greensters" while away the morning on the trunk of a red maple growing at a 45-dgree angle out of the lake bottom. One keeps peering at the ground a foot or so below, looking for signs of prey, then falls off, only to reappear minutes later. Another ventures up the tree, glancing back at its companion, bobbing its head and widening its jaw like a male. But it doesn't possess the mature male's swollen dewlap, which is thought to attract a female.
Sometimes an anole's clumsiness will cause a leaf to flip over, allowing you to discover an otherwise "invisible" lizards. One morning, a restless specimen almost falls out of small alder. I notice it's clothed in a mottled array of orange specks on a light brown head; it has greenish, rib-protruding flanks and brown stripes paralleling its dorsal median.
The green anole may be active well into the fall, even in its northernmost range. On a balmy day in late October, I spot one in a brown coat, descending a tall pine. As it drops to the ground and stumbles over a blanket of brown, crinkly leaves on the forest floor, I track it closely to see if it would feel threatened enough to turn an "excitable" or "worrisome" green. But even after some minutes, its hue doesn't change. Doesn't it feel agitated or threatened? Perhaps it doesn't regard the human presence as a bona fide threat to its well-being.
Anyway, the lizard stays brown. It may not know it's brown. Yet, by remaining so, it has inadvertently kept the very color best fitted to fool the eye of any real enemy--like a bird, a turtle, or a big frog, perhaps.
What would it have taken to cause a stir in the anole's three-chambered heart? Had it been picked up, would that have made a difference? Had it been held by its tail, would it, like a claw-shedding crab, have dissociated itself from its appendage to escape? Indeed, the tail does have a break-off point.
But such artificial intrusions might not have accurately revealed the anole's behavior in the wild. So it's allowed to lose itself in the leaves--leaves that continue to crackle underfoot as "Dr. Doolittle" chooses a divergent path.
William D. Weekes Sr. is a freelance writer based in Spartanburg, South Carolina. He has a background in wildlife science and is a former science teacher and newspaper journalist. He wishes to thank John Green, executive director of the Spartanburg Science Center, for his expert review of the article. An earlier version of this article appeared in Federation Record (September 1993), a publication of the Virginia Wildlife Federation.
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|Author:||Weekes, William D., Sr.|
|Publication:||World and I|
|Date:||May 1, 1998|
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