Hiding in plain sight

Hiding in plain sight
Camouflage, also known as cryptic coloration, is the one-size-fits-all defense in the world of animals. Animals as small as insects and as large as the boldly patterned giraffe—towering at a height of 18 feet (6 m)—depend on their cryptic colorations to help them blend in.

Colors and patterns may camouflage an animal not only by helping it blend in, but also by breaking up its shape. That way, a predator does not recognize it at first. An animal’s coloring can hide the roundness of its body, making it look flat. Colors and patterns also can help hide an animal’s shadow.

Cryptic coloration can be as simple as the sandy fur of a fennec fox, which blends with the tones of its desert home. It can be as complex as the camouflage of a giant swallowtail caterpillar, which looks like a bird dropping on a leaf. The fox “hides in plain sight,” while the caterpillar stays safe by resembling something that does not interest a predator one bit.

Many cryptically colored animals just need to freeze or lie low to be protected. A pointy thorn bug sitting on a stem, for example, looks like a thorn. A grasshopper or katydid that resembles a leaf just needs to sit on a leafy twig to blend in and look like a leaf. Some animals go one step further and behave in ways that enhance their camouflage.

Walking sticks are part of this cast of animal actors. These long, thin insects naturally resemble twigs, complete with sharply bent limbs and bumpy joints. They are closely related to the fantastically shaped leaf insects, which have body parts shaped and colored to look like leaves—right down to leaf veins, nibbled edges, and brown spots of decay. But walkingsticks don’t just look like sticks, and leaf insects don’t just look like leaves. They act like them, too. While sitting still they sway slowly, mimicking the motion of a twig or leaf in the breeze.

Leaf insects have been known to dangle from a stem by one leg, as if they were leaves about to drop. If threatened, many leaf insects will fall to the ground, landing on their feet and scuttling away.

Other insects imitate plant galls, seeds, and flowers. The African flower mantis takes on the coloring of the flower on which it lives. This is also true of the Malaysian orchid mantis, which has legs that look like flower petals. The camouflage patterns on many moths’ wings imitate patterns of tree bark and the lichen growing on it.

Moths instinctively use this camouflage to their advantage. The pine hawk-moth perches on a tree with its head pointing up. This lines up the stripes on its wings with the bark’s furrows. The waved umber moth perches sideways on trees. That’s because its stripes run across its wings. The sideways perch lines up these stripes with the bark’s pattern.

Among the insects, caterpillars excel at combining cryptic coloration with deceptive behavior. A caterpillar’s job is to eat and grow while avoiding being eaten by birds. A caterpillar must also avoid tiny wasps eager to lay their eggs on it. The eggs hatch into larvae that feed on the caterpillar.

A Costa Rican rainforest species of moth caterpillar called Navarcostes limnatis looks like a diseased leaf covered with fungus. It adds a rocking motion to this disguise so that it appears to be quivering in a breeze. Another caterpillar, the larva of a butterfly called the meander leafwing, crawls to the tip of a leaf after hatching. It eats the parts of the leaf that stick out on either side of the sturdy rib running down the leaf’s middle. Then it sits on the rib so that it looks like a bit of nibbled leaf itself. The caterpillar will continue to eat the leaf over the next few days. It binds scraps of leaf to the rib with silk secreted by its body and hides among them.

Insects are stars when it comes to combining camouflage with a convincing performance, but other animals also use this tactic. The leafy sea dragon of Australian waters is one example. It has frills that make it look like a bit of drifting seaweed. The sea dragon also rocks slowly and rhythmically, mirroring the swaying of seaweed in its habitat.

Half a world away, the leaf fish of South America’s Amazon River floats slowly on its side, its flattened, brown body resembling a dead leaf drifting in the water. Its snout looks like the leaf’s stalk. This behavior allows the fish to avoid predators and hunt its own prey without being noticed.

Many tree frogs also imitate leaves or other plant parts. The red-eyed tree frog, for example, snuggles into the curve of a leaf during the day. Its bright green body blends with the leaf. The frog tucks its legs and big orange feet close to its blue-and- yellow sides so that the vivid colors are hidden. Finally, it closes its bulging red eyes, hiding them under gold-flecked lids. The frog can see through these lids to watch for danger as it naps.

Even some larger animals manage to pull off the trick of resembling an object. The potoo, a nocturnal bird of Central and South America, spends the day perched on a dead branch. Its feathers, mottled with brown and gray, work as camouflage. The potoo holds its body at an angle that makes it look like just another dead branch. On the other side of the globe, a look-alike nocturnal bird called the tawny frogmouth poses the same way.

Another bird actor is the American bittern, which lives in wetlands. When it is startled, it stretches its long, thin neck and body and points its sharp bill to the sky. In this position, the streaks of brown running down its breast blend in with the tall, grassy plants around it. The bittern also sways gently, just like the breeze-ruffled reeds.