Why does the professor mention the tiger?

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问题
Why does the professor mention the tiger?
Listen to part of a lecture in a biology class.
Professor: In the animal kingdom, camouflage is a common strategy to avoid predation. There are many examples. The most famous might be the chameleon, a lizard that can change its skin color to match its surroundings, but there are also insects that look like leaves or flowers, frogs that look like rocks. I’m sure you could think of a dozen more examples. First of all, let me introduce a technical term that’s often used for camouflage, and that’s "crypsis."
    When we examine crypsis in the animal kingdom, it may appear that there are a thousand different patterns animals use to hide from predators. However, recent research involving cephalopods is teaching us there is actually less there that meets the eye.
    Squid, octopus, and cuttlefish are cephalopods, and they are uniquely suited for crypsis research because individual animals don’t have a fixed coloration. They actually can very quickly change the appearance of their skin to match almost any habitat. Cephalopods can produce up to 50 different colors, patterns and textures, but what the research is showing is that all these patterns employed by the cephalopods are variations on just three basic types of crypsis.
    The first is uniform or stipple. The word "stipple" is taken from visual arts. It means making small dots to create the impression of a solid color. Anyway, uniform or stipple body patterns are used by cephalopods to match their skin color to fairly uniform backgrounds like the sandy sea bottom. A sandy sea bottom has one basic color with little variation, so an octopus would only need to change its skin color to one basic color to match the environment.
    When a cephalopod needs to blend into a non-uniform, a more varied background, like gravel, which is made up of small rocks of various sizes and colors, the cephalopods choose a mottled body pattern. Mottled body patterns consist of alternating, irregularly shaped dark and light patches in the skin that roughly match the size of the dark and light objects in the immediate area.
    And finally, cephalopods also use what’s called "disruptive coloration." Disruptive body patterns are irregular patches of different shapes and colors that serve to distract an observer’s attention and obscure the outline or true shape of the animal. In other words, a disrupted pattern makes it difficult the shape and size of the animal. Disruptive patterns can also achieve some level of general resemblance to the background. That is, they often contain small regions with mottled patterns or even uniformity. Cephalopods will adopt this crypsis strategy when the background is irregular and contains relatively large and irregular patches of colors and textures.
    You may be asking yourselves why studying cephalopod crypsis is important. Well, while evolution has produced a wide variety of body colorations and patterns in the animal kingdom, the basic pattern types we’ve observed in cephalopods are used throughout the animal kingdom and ecological habitats, and that goes not just for animals that can change their cryptic pattern, but also for animals that have just one cryptic pattern they cannot change. You could also come to the conclusion that these are same basic strategies used by the chameleons, frogs and insects we talked about, and by larger animals as well. For example, the tiger’s pattern of black strips on a lighter background is a form of disruptive coloration.

选项 A、To point out how different its crypsis strategy is from the strategy used by smaller animals
B、To argue that predators rely on crypsis less than prey species do
C、To illustrate that results of the cephalopod research can be extended to many other animals
D、To give an example of an animal whose crypsis strategy has been extensively studied

答案C

解析 组织结构题。线索词为For example,教授在讲座结尾部分总结道:You could also come to the conclusion that these are same basic strategies used by the chameleons,frogs and insects we talked about,and by larger animals as well.即这些基本隐蔽策略不仅适用于变色龙、青蛙、昆虫等小型动物,同样也适用于(像老虎这样的)大型动物。即对于头足类动物的研究也可以拓展到其他动物,因此C选项是正确答案。该部分重点强调小型和大型动物在隐蔽方法上的共性,并非进行对比,因此A选项不正确。教授未将捕食者和被捕食者在隐蔽方法的依赖程度进行对比,因此B选项不正确。该部分未提到老虎已被广泛研究过,因此D选项不正确。
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