Animal Signals in the Rain Forest
The daytime quality of light in forests varies with the density of the vegetation, the angle of the Sun, and the amount of cloud in the sky. Both animals and plants have different appearances in the various lighting conditions. A color or pattern that is relatively indistinct in one kind of light may be quite conspicuous in another.
In the varied and constantly changing light environment of the forest, an animal must be able to nd visual signals to members of its own species and at the same time avoid being detected by predators. An animal can hide from predators by choosing the light environment in which its pattern is least visible. This may require moving to different parts of the forest at different times of the day or under different weather conditions, or it may be achieved by changing color according to the changing light conditions. Many species of amphibians (frogs and toads) and reptiles (lizards and snakes) are able to change their color patterns to camouflage themlves. Some also signal by changing color. The chameleon lizard has the most striking ability to do this. Some chameleon species can chan必须造句
ge from a rather dull appearance to a full riot of carnival colors in conds. By this means, they signal their level of aggression or readiness to mate.
叶问三
Other species take into account the changing conditions of light by performing their visual displays only when the light is favorable. A male bird of paradi may put himlf in the limelight by displaying his spectacular plumage in the best stage tting to attract a female. Certain butterflies move into spots of sunlight that have penetrated to the forest floor and display by opening and closing their beautifully patterned wings in the bright spotlights. They also compete with each other for the best spot of sunlight.
Very little light filters through the canopy of leaves and branches in a rain forest to reach ground level—or clo to the ground—and at tho levels the yellow-to-green wavelengths predominate. A signal might be most easily en if it is maximally bright. In the green-to-yellow lighting conditions of the lowest levels of the forest, yellow and green would be the brightest colors, but when an animal is signaling, the colors would not be very visible if the animal was sitting in an area with a yellowish or greenish background. T
he best signal depends not only on its brightness but also on how well it contrasts with the background against which it must be en. In this part of the rain forest, therefore, red and orange are the best colors for signaling, and they are the colors ud in signals by the ground-walking Australian brush turkey. This species, which lives in the rain forests and scrublands of the east coast of Australia, has a brown-to-black plumage with bare, bright-red skin on the head and neck and a neck collar of orange-yellow looly hanging skin. During courtship and aggressive displays, the turkey enlarges its colored neck collar by inflating sacs in the neck region and then flings about a pendulous part of the colored signaling apparatus as it utters calls designed to attract or repel. This impressive display is clearly visible in the light spectrum illuminating the forest floor.
Less colorful birds and animals that inhabit the rain forest tend to rely on other forms of signaling other than the visual, particularly over long distances. The piercing cries of the rhinoceros hornbill characterize the Southeast Asian rain forest, as do the unmistakable calls of the gibbons. In denly wooded environments, sound is the best means of communication over distance becau in comparison with light, it travels with little impedi
ment from trees and other vegetation. In forests, visual signals can be en only at short distances, where they are not obstructed by trees. The male riflebird exploits both of the modes of signaling simultaneously in his courtship display. The sounds made as each wing is opened carry extremely well over distance and adverti his prence widely. The ritualized visual display communicates in clo quarters when a female has approached.
Paragraph 1: The daytime quality of light in forests varies with the density of the vegetation, the angle of the Sun, and the amount of cloud in the sky. Both animals and plants have different appearances in the various lighting conditions. A color or pattern that is relatively indistinct in one kind of light may be quite 拌牛肉conspicuous in another.
1. The phra conspicuous in the passage is clost in meaning to （2）
○Common
○Noticeable
○Different
玉米骨头汤
○Colorful
Paragraph 2: In the varied and constantly changing light environment of the forest, an animal must be able to nd visual signals to members of its own species and at the same time avoid being detected by predators. An animal can hide from predators by choosing the light environment in which its pattern is least visible. This may require moving to different parts of the forest at different times of the day or under different weather conditions, or it may be achieved by changing color according to the changing light conditions. Many species of amphibians (frogs and toads) and reptiles (lizards and snakes) are able to change their color patterns to camouflage themlves. Some also signal by changing color. The chameleon lizard has the most striking ability to do this. Some chameleon species can change from a rather dull appearance to a full riot of carnival colors in conds. By this means, they signal their level of aggression or readine
腼腆造句ss to mate.
2. According to paragraph 2, what is problematic about an animal's nding visual signals to members of its own species? （1）
○Signs that make an animal visible to its species also make it visible to predators.
○An animal that changes color to avoid predators can confu members of its species.
○Changing light may require an animal to move beyond the visual range of other members.
○The animal may mistakenly signal aggression when it meant to signal readiness to mate.
3. The word 自然景观signal in the passage is clost in meaning to （3）
○change
○imitate
○communicate
○hide
4. According to paragraph 2, all of the following are reasons amphibians and reptiles change color EXCEPT 朱六一(1)
○changing asons
○to signal others of their species
○to match the light
○to hide from predators
Paragraph 3: Other species take into account the changing conditions of light by performing their visual displays only when the light is favorable. A male bird of paradi may put himlf in the limelight by displaying his spectacular plumage in the best stage tting to attract a female. Certain butterflies move into spots of sunlight that have penetr
分隔符怎么插入ated to the forest floor and display by opening and closing their beautifully patterned wings in the bright spotlights They also compete with each other for the best spot of sunlight.
