Day 56

Passage 56

Bats

①

Bats are mammals belonging to the Chiropteraorder, a name of Greek origin meaning“hand-wing”, which accurately describes the animal's most unusual anatomical feature. The Chiropteraorder is divided into two suborders, the Megachiroptera, consisting of a single family, in which there are flying foxes and their fruit and flower eating relatives, and the Microchiroptera, composed of the rest of the bat families. These families are further classified into over 1,000 species, a number making them one of the most prevalent orders of mammals. In fact, more than a quarter of the total number of mammal species are batspecies.

②

Despite the name, not all megabats are larger than microbats; the major distinction between them is not based on their size but on other features. Most megabats are vegetarians and are characterized by a long muzzle which can help them feed on fruit, pollen, or nectar, while most microbats are typically carnivores that have pushed-in snouts and feed primarily on insects, with some feeding on frogs, fish, rodents, even other bats or blood. In addition, the ears of microbats do not form a closed ring but the edges are separated from each other at the base of the ear. Consequently their “vision” can depend on an acoustic orientation called echolocation, which most megabats lack except the Egyptian fruit bats. Besides, microbats lack the claw at the second toe of the forelimb; they also lack underfur and are either naked or have guard hairs.

③

Bats are nocturnal animals, which provide them with certain advantages. Enormous numbers of insects fly at night and, with the exception of spiders, there are few competitors for such food. The darkness also helps them avoid predators, like certain kinds of hawks, snakes and toads. Furthermore, night brings cooler temperatures and higher humidity which help dissipate the heat generated by the muscular activity of flight and help the bat maintain its body temperature and moisture. Because the bat has a thin wing membrane, flying during the heat of the day could be hazardous because of the excessive absorption of heat and the resulting dehydration and possible heat prostration.

④

As we mentioned above, many bat species have developed a remarkable navigation system called echolocation to help them locate and catch prey in the dark. The process that makes this happen is pretty simple: they emit a series of supersonic cries through the mouth or nose and detect flying insects by the echoes reflected back. The bat can achieve various goals with the help of this equipment. It can figure out how far away an object is by determining how long it takes a noise to return, or how big an insect is by sensing the intensity of the echo. It can determine whether the insect is moving away or moving near based on the pitch of the echo, or even tell if an insect is to the right or left by comparing when the sound reaches its right ear with when the sound reaches its left ear: if the sound of the echo reaches the right ear before it reaches the left, the insect is obviously to the right. Besides, the bat's ears have a complex collection of folds that help it determine an insect's vertical position. Echoes coming from below will hit the folds of the outer ear at a different point than sounds coming from above, and will sound different when they reach the bat's inner ear.

⑤

Most bat species are not only harmless to humans, but actually are beneficial. The little brown bat, one of the most common North American bat species, can catch and eat as many as 1,200 mosquitoes in one hour. The famous colony of Mexican free-tail bats will eat up to 30,000 pounds of insects in a single night. These bats and many other species feed on insects that destroy crops, providing an invaluable service to farmers. Bats are also beneficial as plant pollinators. Many species, particularly those in the tropical rainforest, feed on plant nectar, gathering pollen on their bodies as they feed and spreading it when they fly away, helping the plant disperse its seed.

——2012年8月19日北美考试机经

All the following are differences between megabats and microbats EXCEPT .

A. their eating habit

B. their appearance

C. their hearing system

D. their size

核心词汇：

词汇练习：

阅读下列句子，用所给单词的正确形式填空。

navigation compose vertical prevalent carnivore pollinator competitor distinction relative absorption locate consist emit supersonic reflect intensity classify colony maintain disperse hazardous

1. Play is easier to define with examples than with concepts. In any case, in animals it _____ of leaping, running, climbing, throwing, wrestling, and other movements, either along,with objects,or with other animals.(TPO-30:Role of Play in Development)

2. The young of ground-nesting warblers produce begging cheeps of higher frequencies than do their tree-nesting_____.(TPO-11:Begging by Nestlings)

3. In many marine creatures, however, the skeleton is _____ of a mineral variety of calcium carbonate called aragonite.(TPO-20:Fossil Preservation)

4. Long and often lyrical descriptions of the different types of ware exist that assist in pots, although these sometimes confuse an already large and complicated picture. (TPO-10:Chinese Pottery)

5. Two species of deer have been _____ in the Puget Sound area of Washington State in the Pacific Northwest of the United States. The black-tailed deer, a lowland, west-side cousin of the mule deer of eastern Washington, is now the most common. The other species, the Columbian white-tailed deer, in earlier times was common in the open prairie country; it is now restricted to the low, marshy islands and flood plains along the lower Columbia River.(TPO-4:Deer Populations of the Puget Sound)

6. In order to create a sense of structure to this picture, researchers have relied on a distinction that still underlies the forms of much indigenous visual culture—a _____between geometric and figurative elements. (TPO-23: Rock Art of the Australia Aborigines)

7. While agriculturalists rely on domesticated plants, pastoralists rely on domesticated animals. As a result, pastoralists, like _____ in general, occupy a higher position on the food chain.(TPO-14:Pastoralism in Ancient Inner Eurasia)

8. Without predators, the species that is the best _____ for food, shelter, nesting sites, and other environmental resources tends to dominate and exclude the species with which it competes.(TPO-27:Predator-Prey Cycles)

9. Predators are an essential factor in _____ communities that are rich and diverse in spe-cies.(TPO-27:Predator-Prey Cycles)

10. The group conducting the study concluded from a detailed analysis that impacts from meteorites can indeed be _____ . Although there is always some risk that a large impact could occur, careful study shows that this risk is quite small. (TPO-4: Meteorite Impact and Dinosaur Extinction)

11. Water _____ is greatly reduced; consequently runoff is increased, resulting in accelerated erosion rates.(OG:Desert Formation)

12. The astrolabe had long been the primary instrument for _____ , having been introduced in the eleventh century.(TPO-17:Europe's Early Sea Trade with Asia)

13. Since the steam engine was fired by coal, the large mills did not need to be _____ by rivers,as had mills that used water-driven machines.(TPO-26:Energy and the Industrial Revolution)

14. With a moderate to fairly high net energy yield, these systems _____ no heat-trapping carbon dioxide or other air pollutants and need no water for cooling; manufacturing them produces little water pollution.(TPO-3:Electricity from Wind)

15. The keels, finlets, and corselet help direct the flow of water over the body surface in such as way as to reduce resistance (see the figure). Again, _____ jets have similar features. (OG:Swimming Machines)

16. In addition to dairy farming and cultivating industrial crops, a third sector of the Dutch economy _____ the way in which agriculture was being modernized-horticulture. (TPO-23:Seventeenth-Century Dutch Agriculture)

17.In general,the larger the city,the greater its heat-island_____.(TPO-23:Seventeenth-Century Dutch Agriculture)

18. It was found that when a white-tailed buck makes a rub, it moves both antlers and forehead glands along the small tree in a_____direction.(TPO-28:Buck Rubs and Buck Scrapes)

19. An ant colony may be legitimately called a super organism because its communication system is so highly organized that the _____ always works as a whole and appropriately according to the circumstances.(TPO-19:Succession,Climax,and Ecosystems)

20. The third type of symbiosis, mutualism, benefits both partners in the relationship Legume plants and their nitrogen-fixing bacteria, and the interactions between flowering plants and their_____,are examples of mutualistic association.(TPO-17:Symbiotic Relationships)

21. Unlike aquatic and marine forms, land plants cannot always rely on water currents to carry their sex cells and_____their fertilized eggs.(TPO-25:The Evolutionary Origin of Plants)

参考答案：

1. consists 2. relatives 3. composed 4. classifying 5. prevalent 6. distinction 7. carnivores 8. competitor 9. maintaining 10. hazardous 11. absorption 12. navigation 13. located 14. emit 15. supersonic 16. reflected 17. intensity 18. vertical 19. colony 20. pollinators 21. disperse