Ready, set, action! Meet some of nature's coolest movers and shakers.
GETTING A GRIP
Wild cats are speedy runners, but cheetahs are champs. They can run up to 113 kilometers (70 miles) per hour--faster than any land animal. Their super speed comes in handy when pursuing prey on the African plains. To keep from slipping during a chase, cheetahs rely on the hard pads located on each paw. The pads grip the ground like new car tires grab the road. And their claws work like cleats on a sprinter's track shoe. Together, the claws and pads provide traction as the cat runs. That keeps the cheetah from slipping and skidding at such high speeds.
Bush babies look like tiny streaks of fur bouncing from branch to branch. How do they do it? They use the tendons inside their legs, says Brigitte Demes, a scientist who studies how bush babies move. When a bush baby lands, the stringlike tendons in its legs stretch like rubber bands and store some of the energy from the previous jump. Scientists call the energy that's stored in the tendons potential energy because it has the possibility (potential) of being used in another jump. Boing! The tendons snap back and release the energy. This makes the bush baby leap forward. At the same time, its big ears and keen eyes track insects so it can pounce on them.
When a Wallace's flying frog hops out of a tree in Malaysia, it doesn't drop like a rock. Instead, this frog glides to the ground! This "flying" frog begins its descent by spreading the webbed skin located between its toes. The stretched-out webs make the frog's feet Frisbee-shaped: curved on top and flatter on the bottom. As the frog descends, air flows over the curved top faster than it flows along the flat bottom. The slower-moving air on the bottom pushes up on the foot more than faster-moving air pushes down. This gives the frog lift, and allows it to glide to the ground instead of falling.
Backswimmers are the scuba divers of the insect world. "They're the only insects that can hover underwater," says Philip Matthews, a scientist who studies them. Matthews recently discovered the secret to the backswimmers' trick.
To hover underwater, a backswimmer breathes in a bubble of oxygen. This bubble helps the insect breathe, and provides buoyancy, which keeps the backswimmer from sinking.
As the backswimmer hovers, oxygen in its bubble starts to decrease. The insect then relies on an extra supply of oxygen stored in the hemoglobin inside its abdomen. It adds oxygen from this supply to its bubble when it needs refilling. This is similar to the way a scuba diver carries extra oxygen in an air tank. The stored oxygen allows the backswimmer to breathe and stay buoyant for four extra minutes. And that's bad news for the tiny underwater creatures it likes to eat.
Word to Know
Prey--an animal hunted for food
Traction--the gripping power that keeps a moving body from slipping on a surface
Tendon--a tissue that connects muscle to bone
Potential energy--energy stored by an object
Lift--an upward force
Buoyancy--the ability to float in a liquid or rise in a gas
Hemoglobin--a substance in red blood cells that carries oxygen to all parts of the body
1. What part of a cheetah's body helps keep it from slipping?
A. the pads on its paws
B. its hind legs
C. its claws
D. both A and C
2. A bush baby stores potential energy needed for jumping --.
A. in the tendonds in its legs.
B. in its tail
C. in the pads on its paws
D. in its abdomen
3. What is a backswimmer's bubble filled with?
B. red blood cells
1. D 2. A 3. C
SCIENCE CONTENT STANDARDS
For Grades K-4
* Position and motion of objects
* Characteristics of organisms
For Grades 5-8
* Motion and forces
* Diversity and adaptations of organisms
INTEGRATE YOUR CURRICULUM!
Language Arts--Reading comprehension
Set a Purpose
To learn about how types of animals move.
* A cheetah may run fast, but it can only maintain its top speed for a few seconds. Therefore, when a cheetah hunts, it stalks its prey and gets as close to it as possible before sprinting toward it.
* Bush babies have very delicate ears. When leaping through thorny bushes, they fold their ears against their heads to protect them.
* The backswimmer swims upside down. It uses its oar-like legs to paddle through water.
* Wallace's flying frog can glide up to 15 meters (50 feet) between trees. It's feet work like suction cups, helping the frog grab onto a surface when it lands.
* What are some animals that move differently than humans? (Possible answers: birds, dolphins, horses.)
* How do these animals move? (Possible answers: Birds fly; dolphins swim, and horses gallop on all fours.)
* What enables these animals to move in such ways? (Possible answers: Birds have wings; dolphins use their fins and tail to swim; horses have powerful legs.)
* If a Wallace's flying frog didn't have the skin between its toes, what would happen? (Possible answers: It would fall to the ground and hurt itself; it wouldn't be able to glide.)
* What kinds of inventions have humans made to help them float fromt he sky to the ground like flying frogs? (Possible answer: Parachutes, hang gliders.)
* www.kidshealth.org/kid/body/muscles_SW.html This Web page features in-depth, but kid-friendly, explanations of the parts of muscles and how muscles work.
* How Animals Move (Animal Survival) by Michael Barre (Gareth Stevens Publishing, 1998) explains how animals have different ways of moving around in their environments.
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|Title Annotation:||animal locomotion|
|Article Type:||Cover story|
|Date:||Nov 1, 2006|
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