托福閱讀聽力寫作 demo 08 The humpback whales issue

 

托福閱讀聽力寫作 demo 08    

The humpback whales issue

    by David pai

TOP 49.

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Like many creatures, humpback whales migrate long distances for feeding and mating purposes. How animals manage to migrate long distances is often puzzling. In the case of humpback whales, we may have found the answer: they may be navigating by the stars, much as early human sailors did. What we know about humpback whales makes this a distinct possibility.

First, humpback whales seem to be intelligent enough to use stars to navigate by. Whales' brains have a high degree of complexity,'a common determiner of intelligence’. This suggests that the whales' brain power far exceeds that of most other animals. The whales' well-developed cognitive ability seems to provide a sound basis for the ability to use a complex, abstract system of sensory stimuli such as the night sky for orientation.

 Second, humpback whales migrate in straight lines. Animals can maintain movement in a straight direction for long distances only if they orient themselves by some external objects or forces. Many birds and other terrestrial creatures, for example, use physical landmarks to help them stay on track as they migrate. Whales, which swim in the open ocean, cannot rely on land features; they could, however, rely on stars at night to provide them with external signs by which to maintain direction over long distances.

Third, humpback whales exhibit an unusual behavior: they are sometimes observed floating straight up for minutes at a time, their heads above the water as though they were looking upward. The behavior is known as spy-hopping, and it is very rare among marine animals. One explanation for the function of spy-hopping is that the whales are looking at the stars, which are providing them with information to navigate by.

 Listening:

Professor: The theory that humpback whales use the stars to navigate the open seas is a fascinating one, but the evidence supporting the theory is not very convincing.

First, there doesn’t seem to be any real connection between intelligence and an animal's ability to use stars for navigation. You know, there are other animals that use stars to navigate. Some birds have this ability, like ducks for example. Now the general cognitive ability of ducks is only average. They are not highly intelligent. The fact that the ducks evolved the ability to use stars for navigation does not seem to have much of a connection to their overall intelligence. It's just an instinct they were born with, not a sign of intelligence. So the fact that humpback whales happen to be intelligent does not make them particularly likely to use stars for navigation. The two things just don't seem to be connected.

 Second, there may be a different explanation for the humpback whale’s ability to navigate in straight lines. Remember that for animals to be able to do this, they have to sense some external object or force. Well, the external force the whales could be sensing is Earth’s magnetic field. Humpback whales have a substance in their brains called biomagnetite. Generally, the presence of biomagnetite in an animal’s body makes that animal sensitive to Earth’s magnetic field. The fact that there’s biomagnetite in the brains of humpback whales suggests that they orient themselves by the magnetic field rather than the stars when they migrate.

 Third, spyhopping probably has nothing to do with looking at stars. Spyhopping is rare, but there are other animals that exhibit it. Some sharks do it, for example. But sharks don't migrate or look at stars. Sharks spyhop to look for animals they want to hunt. And another thing, humpback whales often spyhop during the day, when no stars can be seen. So to suggest that the function of spyhopping is to look at stars is pure speculation.

 summary

In the lecture,the professor disappove each the author’s (explainitory) points that support the hypothesis that humbwhale is able to migrate long distance by stars-the sophisicated brian,straight-line migration ability,and the spy-hopping behavior,and give an array of(=some) counter views. Below are the details

First, the professor don’t acknowledge that the intelligence has much to do with their long migrating ability by giving an example of ducks without high intelligence but with the ability of star detection

Second, the professor think it is likely that the humbback whale may rely on earth-magnet-detecting ability rather than start-cognitive one . One substance, biomagnetite,exist in their brain and help do the orientation function and make them able to do straight-line long migration..(linking mechanism)

Last, the professor indicates shark also does the spy hopping ,but they use it for preying; this may imply the prematureness of assumption that humbback whale use it for seeing the star.