From: eNature.com
Published November 30, -0001 12:00 AM

Blend for Your Life!

Some animals run for their lives when they sense danger, but others do the opposite: they stand still. These animals blend in so well with their backgrounds they are safer if they freeze in the presence of danger. Meanwhile, on the top of the food web, predators are camouflaged, too, sneaking up on unsuspecting prey who don't see them until it's too late.


Now You See It, Now You Don't


Camouflage takes many guises in the animal world. There are numerous species that have cryptic coloring that enables them to blend in with their environment. Pocket gophers, for example, tend to have fur the same shade of brown as their local soil, no matter what species they are. There are salamanders with a color pattern that resembles lichens, fish shaped like sea grasses and others that match gravelly or sandy bottoms, insects that look like sticks or leaves, moths in the various colors and patterns of tree bark, and snakes that blend in with the desert sand.


The Granite Lizard is patterned to match the rock in the areas in which in lives. In fact, this lizard comes in two forms, one with a bold granite-like pattern that lives among granite outcrops and one with a subdued sandstone coloration that lives in sandstone. The black-and-white granite subspecies would stick out like a sore thumb in some environments, but on a speckled granite backdrop it blends right in.


A few kinds of animals, including some reptiles and fish, can change their color or pattern when they move from one environment to another. Small lizards called Green Anoles don't always match their name -- especially when they turn brown to blend in with the background. These chameleon relatives can change color in seconds, matching green leaves and brown branches alike.


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Some animals are camouflaged to look like something else entirely. The Giant Swallowtail Caterpillar has a blotchy dark brown and white pattern that makes it look like a large bird dropping. Most predators aren't interested in droppings and will pass it by. The leaf-like katydid and the walkingstick are other insects that look so much like parts of their environment they can be almost impossible to see until a movement gives them away.


Heard but Not Seen


Many people who have heard a Whip-poor-will have never seen one. These birds and their relatives such as the Common Poorwill and Chuck-will's-widow are named for their distinctive calls. Lucky for them they weren't named for their looks, because they resemble nothing so much as a pile of dead leaves and old twigs. These birds are active at night, gobbling insects in their wide-gaping mouths. During the day they rest, usually on the ground, where they so effectively blend in with the leaf litter they essentially disappear from sight.


Treefrogs, similarly, make a racket with their calling, but when was the last time you actually spotted one? These little creatures are often the bright green of spring leaves and dozens of them can disappear on a single tree. The gray treefrog can look for all the world like the bark of a tree. You could pass right by it without ever noticing, which is the whole point, for there are those in the world who consider this little frog a very tasty morsel.


Sneak Attack<


Camouflage serves both predator and prey--and in some cases both at once. Animals that are food for other animals employ camouflage so that predators, from sharp-eyed owls and hawks to sharks, bears, weasels, and snakes, don't see them. If they can look enough like a bunch of old leaves, a patch of lichens, or a nice green leaf, that hungry owl or badger just might pass on by.


Likewise, predators are sometimes cryptically colored so that they can sneak up on prey without being seen. Think of the Polar Bear, top of the Arctic food chain, colored to match its snowy background. The Great White Shark is dark on top and light below. This pattern, called countershading, helps it blend in with the dark depths when seen from above and with the brightness from the sky when viewed from below.


The Goosefish lies in wait on the ocean floor, looking like a sandy lump and wiggling a little appendage that serves to lure unsuspecting fishes near. Once a fish goes for the lure, the Goosefish rises up and swallows it. When the dust clears, this voracious predator has again settled into the sand, stock-still, except for its gently waving lure.


The diminutive Long-tailed Weasel is one of many creatures that plays both roles, predator and prey. Its changing coloration (snow-white in winter, brown in summer) helps it hide from foxes, cats, and birds of prey, while stalking a shrew, mole, or bird for its own meal. It's a predator-eat-prey world out there -- and sometimes a predator-eat-predator world -- and every survival tactic helps. Sometimes the smartest thing to do is stand still, and blend for your life.


To learn more about some of these masters of camouflage, click on the pictures at the botton of this page.



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