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Zoo-ology column: Some animals master cryptic coloration

Oct. 23, 2011 at 5:23 a.m.

A Gumleaf Grasshopper uses camouflage to make itself less visible among leaves and twigs.

Have you ever flushed an unseen covey of quail? After your head stopped spinning around and you could breathe normally again, you realized what happened. The quail, now gone, were camouflaged. Using colors that blend, to hide or hunt, is called crypsis or cryptic coloration. In mimicry, a species is visible, but mimics something else; camouflage makes an animal less visible.

Some camouflage may not seem all that great to our eyes, but animals, like people, may see things differently. Some are color blind or nearsighted and even the placement of their eyes makes a difference allowing monocular or binocular vision.

Cryptic coloration can create visual confusion using patterns that break up an animal's outline. Zebras are a perfect example. Their main predators, lions, are color blind. Zebras are usually found in herds and most likely noticed, but what would they look like to a lion? Possibly a big mass of light and dark. The overall stripe pattern of the group disrupts a single zebra's outline. Let's say the lion does pick out a single zebra, but suddenly the herd scatters. The lion may be in a quandary as the mass of light and dark moves every which-way and the chosen zebra blends into it. The lion may be confused and decide not to dive into the moving mass.

A tiger's pattern blends perfectly with the color and shadowy areas of grasslands where they live. Spots on animals work the same way.

Many animals are so good at hiding they can be hard to see even when you know they're there. Finding a screech owl is quite difficult if it doesn't want to be seen. It stretches upward making its feather patterns look like tree bark. It may even squint or close its eyes so there's no chance of a reflection to give its location away.

Cryptic coloration may be similar all-over color, like a polar bear in snow. The snowshoe hare, rusty brown in the summer, changes to white in winter.

Counter shading is a clever form of crypsis where an animal has different colors on its back and underside. Generally daylight makes upper parts brighter and lower parts shaded. In counter shading, the colors are reversed. If a fish is looking up for a meal, the prey that is lighter underneath would be harder to see against the brighter water surface. If the fish is looking down, the prey with a dark or sometimes patterned back would blend in with the depths. Penguins and many other species use counter-shading.

Crypsis is found throughout the natural world. Many insects are masters of cryptic coloration. They may visually disappear among leaves. Not only do many of them look like green or dried leaves, sticks or bark - they may even move like them. There are butterflies that look like dried leaves, praying mantises that look like dying leaves, even a moth that looks like bird droppings.

WHO or WHAT will be cryptically colored at the Haunted Zoo? Come if you dare and be prepared for frightful fun. Oct. 28 & 29 7-11 p.m. Admission $5 each (not recommended for young children.) For a trick or treat friendly ZooBoo, bring your younger family between 10 a.m. and 3 p.m. Regular Zoo Admission.

Judie Farnsworth is a longtime volunteer at the Texas Zoo specializing in educational programs.

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