Color Change A desert chameleon can’t easily find water. So it has a diff erent way to beat the heat. Normally, this chameleon is muddy brown with pale spots on its sides. It has red ridges above its eyes and yellow stripes under its chin. It walks stiffly across the desert. Making
its legs straight and long helps it keep its belly away from the hot sand. T at’s one way this chameleon keeps cool. It’s not the only way. As it walks, it suddenly seems to disappear.
It didn’t. It changed color. Now it is mostly white, yellow, and gray. T e color of its scaly skin matches the color of the sand. Unlike many chameleons, this one doesn’t
change color just to show its moods. It changes color to stay cool. T e paler its skin, the more it reflects
the sun. So most of the heat bounces off the chameleon’s skin. Now this chameleon can wander the desert and not get too hot. T e chameleon uses unique parts in its skin
to quickly change color. T ese parts can grow and shrink. When they shrink, the chameleon’s colors fade. When they expand, the chameleon turns dark. T at’s what happens when this reptile gets
too cold. T e darker colors absorb heat. T e chameleon warms up.
Big Bill A toucan uses a body part to control its body temperature, too. It uses its big, colorful bill. Its bill puzzled scientists for a long time.
T ey thought maybe it helped the bird pick fruit. Now they have a new idea. Using a special video camera that detects
heat, they recorded the bird. When they watched the video, they got a big surprise. Almost all of the bird’s body heat escapes through its bill. T e bird’s blood carries its body heat. If
the toucan gets too hot, it sends extra blood to its bill. As the blood circulates through the bill, heat escapes. A toucan can drop its temperature nearly 6°C (10°F) in minutes.
8 NATIONAL GEOGRAPHIC EXPLORER
Fast Fact: Yawning may help cool your brain.
Super Size An African elephant’s ears work a lot like the toucan’s bill. Heat escapes as blood rushes into the elephant’s big, thin ears. An elephant also flaps its ears and sprays them with water. By doing this, the elephant can drop its body temperature by 5°C (9°F). A fennec fox has a similar way to stay cool
in the Sahara. T is desert fox is the smallest fox in the world. Yet there’s nothing small about its ears. T ey stick up from its head as much as 15 centimeters (6 inches). When it gets too hot, the fox sends extra
blood to its ears. It has less fur on its ears than on its body. So it’s easier for heat to escape. T e fox has a second way to keep cool, too.
It only goes out at night. T at way, it avoids the hot sun altogether. Many more animals have wild ways to beat
the heat. A polar bear rests. A fiddler crab lets heat escape from its giant claw. Some birds fl y up high where the air is chillier. For all of these animals, staying cool means staying alive. Now that’s pretty cool.
Wordwise
behavioral adaptation: an action that helps an animal survive
body temperature: the degree of coolness or heat inside an animal’s body
cold-blooded: able to use the environment to control body temperature
physical adaptation: a body part that helps an animal survive
warm-blooded: able to make heat to control body temperature
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