Animal action stars! Animals make amazing moves to nab their every meal.

What does this leaping bush baby have in common with a slithery snake or quivering jellyfish? From wild forests to deep oceans, these predators need physical prowess to capture and feed on other animals to survive.

Much like an elite athlete's physique is honed for medal-winning performance, each of these predators is uniquely adapted for nabbing prey. "No animal is haphazardly designed," says primate expert Ken Glander at Duke University. Rather, animals' bodies have evolved to move with the least amount of energy, or with efficiency. Predators can't afford to waste any energy--and energy comes from food. And in nature, snagging food is a lot harder than heading to a local supermarket.

As a predator digests its meal, the food breaks down into chemicals that can be used by body cells. To release energy from these chemicals, the cells break down glucose (or simple sugar) molecules in a process called respiration (see diagram, page 14). Long cells called muscle fibers use energy to contract, or tighten--this is how muscles move. Yet every animal moves in its own way because of its unique morphology, or body design. Check out the designs of these animal action stars.

LONG-JUMP CHAMP

Lesser galago (a.k.a. "bush baby")

The chipmunk-size Galago senegalensis could teach an Olympic long jumper a few points about taking a leap. The longest recorded bush baby jump: 23 feet--just 6 feet shy of the human world record! Not bad for a critter that measures just 160 millimeters (7 inches) and weighs less than a box of macaroni (199 grams).

Galagos, or bush babies, are nocturnal (night-active) primates native to southern Africa. (The primate family includes such mammals as monkeys, apes, and humans.) During their waking hours, bush babies don't bound from tree to tree for mere fun and games--they're tracking insect prey. "The way an animal moves has to do with body type and food preference," Glander explains. A hush baby pounces so it can nab bugs before they dart off.

Luckily, a bush baby's design is perfect for ambushing insects. The animal's keen eyes spy bugs in the dark of night. And those muscular hind legs and long feet function much like the coiled springs in a pogo stick: When a bush baby lands, its leg muscles absorb and "store some of the energy from the previous jump," Glander says. The legs then use that stored energy, plus energy drawn from the muscle cells, to make the next leap. Boing!

MASTER SWIMMER

Jellyfish

Jellyfish may not set ally aquatic speed records, but there's no fish ill the sea that tops these creatures" record for endurance: The fossil record suggests that jellyfish have made their moves for 500 million years. "They may have been the first animals to swim with muscles," says biologist Jack Costello of Providence College in Rhode Island.

The body of a jelly consists of an

outer cell layer, an inner cell layer, and in between a thick gel called mesoglea. This gooey stuff contains muscle fibers that produce swimming pulsations. To swim, a jellyfish sucks water into its underside. Then it contracts its body to squeeze out the water, creating a jet stream that propels the jellyfish in the opposite direction--though not too swiftly. "That hell shape is probably one of the least effective shapes for forward progress," Costello says. Fast swimmers like bar racuda and orcas, for example, tend to be streamlined.

But most jellyfish aren't made for speed, says Costello: "The way jellies swim is related to how they catch food." Recently he discovered that a pulsing jellyfish produces currents that sweep tiny aquatic organisms directly into its stinging tentacles and the mouth opening on its underside. A clever trick, says Costello, "but they've had longer than any other animal group to master it!"

HIGH DIVER

Paradise tree snake

Snakes have the moves. They can slither, they can swim, they can sidewind. And some serpents can even fly! Most so-called "flying snakes" just glide front branch to branch. But a University of Chicago scientist recently discovered that at least one species--the paradise tree snake--can actually transform its body into an airfoil (airplane-wing shape) and steer through the air as expertly as a flying squirrel.

Jake Socha made his discovery by filming snakes taking flight. Socha still doesn't know why the snakes fly (efficiency probably plays a role), but after watching countless hours of footage, he has figured ant how snakes fly. When a paradise tree snake prepares to jump, it hangs from a branch in the shape of a letter J: "The snake then uses its muscles to fling itself up and away from the branch." Once airborne, it flares its ribs so far outward that its whole body flattens (see diagram, below). "In effect, it becomes a flying wing."

The flattened snake then undulates, rippling like the letter S through the air. "That taxes the muscles in two ways at the same time," Socha says. Is this an efficient way to move from point A to point B? "If you're living in a tree and want to reach the next tree," he says, 'I'd bet that the energy expended in gliding is far less than it takes to climb."

HOW SNAKES SOAR

Cross-sections show how a paradise tree snake's body changes from round to flat during "flight."

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ACTION HALL OF FAME

Some of nature's best examples of animal motion are found in a seal, seabird, and big cat. Scientists marvel at these animals' talents. Read on to find out why.

BREATH-HOLDING CHAMP: WEDDELL SEAL

Like all predators, seals survive by capturing and killing prey. But these aquatic mammals hunt deep in the frigid water beneath Antarctic ice--holding their breath the entire time! The Weddell seal breath-holding record: 82 minutes.

BEST FLIER: WANDERING ALBATROSS

"With 10-foot wing spans, albatross can glide across entire oceans on a single wingbeat!" says biologist Terrie Williams of the University of California at Santa Cruz. The seabirds' long, slender wings minimize drag (force that slows movement) so they can ride air currents for tremendous distances while expending little energy.

FASTEST LAND ROVER: CHEETAH

Cheetahs spring at speeds of 114 kilometers per hour (71 mph), but because their muscles are full of fast-twitch fibers--which have few mitochondria (see below)--they run out of gas quickly. They can maintain top speed only for about 274 meters (300 yards). "A cheetah better catch its prey in that distance, or it's not worth the effort," says Duke University professor Ken Glander.

RESPIRATION: HOW CELLS RELEASE ENERGY FROM FOOD

An animal cell has many parts, each one with a specific purpose. One part, the mitochondrion (illustrated below), supplies energy to the rest of the cell. A cell may contain hundreds of the little powerhouses. They turn simple sugar (glucose) molecules into energy.

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It's your choice

After reading the article, choose the correct answer to these questions:

1. Which of the following statements about muscle cells is true?

A. They convert food molecules into energy, B. Like a car engine, they burn fuel to create motion. C. They're long cells. D. All of the above.

2. A bush baby's physiology is adapted primarily for

A. climbing trees. B. gliding through the air like a flying squirrel. C. pouncing on insects. D. swinging from tree to tree.

3. How does a jellyfish capture food?

A. It chases plankton through the water. B. It sneaks up on prey and nabs it with its long stinging tentacles. C. It glides along the ocean floor sucking up snails. D. It pulses its body, creating currents that sweep tiny aquatic organisms right into its tentacles and mouth.

4. Which of the following statements best describes a paradise tree snake's body as it glides through the air?

A. It flattens its body into an airfoil shape and undulates, rippling like the letter S. B. It hangs like the letter J. C. It generates enough force to propel itself upward against gravity. D. It transforms its flat body into a cylindrical, or tubelike, shape and slithers.

1. d 2. c 3. d 4. a

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Did You Know?

* Just like humans, each bush baby has a unique set of fingerprints.

* The jellyfish is so simple in structure--lacking bones, blood, heart, and brain--that biologists once thought it was a plant.

* About five species of Asian tree snares are considered "flying snakes." All glide in a straight line; only the paradise tree snake maneuvers and changes direction in midair.

Cross-Curricular Connection

Math: Biologists use body length as the measure of how far an animal can jump or how fast it can move. For example: A biologist would describe a jellyfish's swimming speed as 5 body lengths per second. And a bush baby might be said to leap 75 body lengths.

* The longest recorded bush-baby leap is 7 meters. If the bush baby is 0.16 m long, how many body lengths is that?

* The human long-jump record is 8.95 meters. Record-holder Mike Powell is 1.88 m tall. How many body lengths did he jump? How does Powell's jumping ability compare with the record-holding bush baby's?

Critical Thinking: Jake Socha, the University of Chicago scientist who studies flying snakes, isn't sure why some snakes have developed the ability to glide. What factors might explain this? Explain the reasoning behind each of your ideas. How might you test your hypotheses?

Resources

Watch scientist Jake Socha's flying-snake footage at www.flyingsnake.org/

To see more bush babies, visit the Duke University Primate Center online at www.duke.edu/web/primate/

For more amazing photos of animals on the go--and other curiosities--check out Weird Nature by John Downer (Firefly Books, 2002).

Animal Action Stars!

Directions: Match the word in the left column with the correct phrase
in the right column.

-- 1. primates       a. using the least amount of energy
-- 2. mesoglea       b. active at night
-- 3. efficiency     c. family including monkeys, apes, and humans
-- 4. airfoil        d. cell part that supplies energy to the rest
                        of the cell
-- 5. undulate       e. jellyfish's muscle fiber-filled gel
-- 6. drag           f. ripple like the letter S through the air
-- 7. nocturnal      g. airplane-wing shape
-- 8. mitochondria   h. force that slows down movement

1. c 2. e 3. a 4. g 5. f 6. h 7. b 8. d