Part II 15 minutes
2Animals on the Move
It looked like a scene from Jaws but without the dramatic music. A huge shark was lowly swimming through the water, its tail swinging back and forth like the pendulum of a clock.
Suddenly sensitive nerve ending in the sharks skin picked up vibrations of a struggling fish. The shark was immediately transformed into a deadly, efficient machine of death. With muscles taut, the shark knifed through the water at a rapid speed. In a flash the shark caught its victim, a large fish, in its powerful jaws. Then, jerking its head back and forth, the shark tore huge chunks of flesh from its victim and swallowed them. Soon the action was over.
Moving to Survive
In pursuing its prey, the shark demonstrated in a dramatic way the important role of movement, or locomotion, in animals.
Like the shark, most animals use movement to find food. They also use locomotion to escape enemies, find a mate, and explore new territories. The methods of locomotion include crawling, hopping, slithering, flying, swimming, or walking.
Humans have the added advantage of using their various inventions to move about in just about any kind of environment. Automobiles, rockets, and submarines transport humans from deep oceans to as far away as the moon. However, for other animals movement came about naturally through millions of years of evolution. One of the most successful examples of animal locomotion is that of the shark. Its ability to quickly zero in on its prey has always impressed scientists. But it took a detailed study by Duke University marine biologists S. A. Wainwright, F. Vosburgh, and J. H. Hebrank to find out how the sharks did it. In their study the scientists observed sharks swimming in a tank at Marine land in Saint Augustine, Fla. Movies were taken of the sharks movements and analyzed. Studies were also made of shark skin and muscle.
Skin Is the Key
The biologists discovered that the skin of the shark is the key to the animals high efficiency in swimming through the water. The skin contains many fibers that crisscross like the inside of a belted radial tire. The fibers are called collagen fibers. These fibers can either store or release large amounts of energy depending on whether the fibers are relaxed or taut. When the fibers are stretched, energy is stored in them the way energy is stored in the string of a bow when pulled tight. When the energy is released, the fibers become relaxed.
The Duke University biologists have found that the greatest stretching occurs where the shark bends its body while swimming. During the bodys back and forth motion, fibers along the outside part of the bending body stretch greatly. Much potential energy is stored in the fibers. This energy is released when the sharks body snaps back the other way.
As energy is alternately stored and released on both sides of the animals body, the tail whips strongly back and forth. This whip-like action propels the animal through the w
3When the shark detects an important food source, take place .
4What is the key to the sharks swift locomotion in water?
AThe skin.
BThe tail.
CThe muscle.
DThe jaw.
5Examples of automobiles, rockets and submarines are used to show that .
Ahumans are the most clever living creatures in the world
Bhuman inventions enable us to travel in almost any kind of environment
Chumans are very successful in inventing transportation tools
Dhumans cant move like other animals in any circumstances
6According to the passage, can be compared to the string of a bow for both of them store energy when stretched .
7According to the Duke University scientists, when does the shark stretch its collagen fibers to the greatest extent?
AWhen moving its tail rapidly.
BWhen finding its preys.
CWhen staying without any movement.
DWhen bending its body in swimming.
8A laminar flow is formed when a fish swims .
Aslowly through the water
Brapidly through the water
Cagainst the current
Dat the fastest speed in water
9Why is the area just under the sharks collagen fibers similar to a belted radial tire?
ABecause it is also full of blood pressure.
BBecause it is also filled of air pressure.
CBecause it is also inflated by pressure.
DBecause it also can be used again and again.
10A shark finds its prey by .
11Consuming the equal amount of energy as a slug does, a mouse can travelas long as it.
Aone twelfth times.
Bthe same.
C12 times.
D1.2 times.