IELTS Academic Reading Practice 29

 
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This reading practice simulates one part of the IELTS Academic Reading test. You should spend about twenty minutes on it. Read the passage and answer questions 15-27.

Questions 15-22

Complete each sentence with the correct ending A-M from the box below.

Write the correct letter A-M in boxes 15-22 on your answer sheet.

NB You may use any letter more than once.

15 Toothed species of cetaceans
16 Baleen species of cetaceans
17 Cetaceans
18 The blowhole area
19 Humpback whales
20 Bottlenose dolphins
21 Chinese baiji
22 Most species of cetaceans

  1. likely can’t see with both eyes
  2. appear to have lost the sense of smell
  3. likely nearly blind
  4. are vocal with good hearing
  5. are very sensitive to touch
  6. likely can see extremely well in water
  7. have moderate vision both in water and in air
  8. are likely blind
  9. are a group of aquatic mammals
  10. likely can see moderately well in water only
  11. have limited acoustic sense.
  12. has extremely keen vision in air
  13. are very sensitive to light
Questions 23-27

Do the following statements reflect the claims of the writer in the reading passage? In boxes 23-27 on your answer sheet, write

YES   if the statement reflects the claims of the writer
NO   if the statement contradicts the claims of the writer
NOT GIVEN   if it is impossible to say what the writer thinks about this

23. It is certain that baleen species are unable to smell.
24. Early experimental evidence indicates that the bottlenose dolphin has good in-air vision.
25. The habitat of clear waters is related to good visual ability.
26. Most large baleens send low-frequency underwater calls to one another.
27. Humpback whales usually hunt in summer.

Answer Sheet
1
2
3
4
5
6
7
8
9
10
11
12
13
14
N/A
15
N/A
16
N/A
17
N/A
18
N/A
19
N/A
20
N/A
21
N/A
22
N/A
23
N/A
24
N/A
25
N/A
26
N/A
27
N/A
28
N/A
29
N/A
30
N/A
31
N/A
32
N/A
33
N/A
34
N/A
35
N/A
36
N/A
37
N/A
38
N/A
39
N/A
40
N/A


  • help Learn how to HIGHLIGHT & ADD NOTES
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    3. RIGHT CLICK SELECTED TEXT

Senses of Whales

Some of the senses that we and other terrestrial mammals take for granted are either reduced, absent, or fail to function well in cetaceans, a group of aquatic mammals which include whales. For example, it appears from their brain structure that toothed species are unable to smell. Baleen species, on the other hand, appear to have some related brain structures, but it is not known whether these are functional. It has been speculated that, as the blowholes evolved and migrated to the top of the head, the neural pathways serving a sense of smell may nearly all have been sacrificed. Similarly, although at least some cetaceans have taste buds, the nerves which serve this function are either underdeveloped or rudimentary.

The cetaceans’ sense of touch has also sometimes been described as weak, but this view is probably mistaken. Trainers of captive dolphins and small whales often remark on their animals’ responsiveness to being touched or rubbed, and both captive and free-ranging cetacean individuals of all species (particularly adults and calves, or members of the same subgroup) appear to make frequent contact. This contact may help to maintain order within a group, and stroking or touching are part of the courtship ritual in most species. The area around the blowhole is also particularly sensitive and captive animals often react very strongly to being touched there.

Vision in cetaceans has developed to be more sensitive in different species. When baleen whale species studied in close quarters underwater, specifically a grey whale calf in captivity for a year, and free-range right whales and humpback whales studied and filmed off Argentina and Hawaii, have obviously tracked objects with vision underwater, and they can apparently see moderately well both in water and in the air. However, the position of the eyes in baleen whale restricts the field of vision to the point that they probably do not have the ability to see stereoscopically like humans do, using both eyes.

On the other hand, the position of the eyes in most dolphins and porpoises suggests that they have stereoscopic vision forward and downward. Eye position in freshwater dolphins, who often swim on their side or upside down while feeding, suggests that what vision they have is stereoscopic forward and upward. By comparison, the bottlenose dolphin has extremely keen vision in water. Judging from the way it watches and tracks airborne flying fish, it can apparently see fairly well through the surface of the water as well. And although preliminary experimental evidence suggests that their in-air vision is poor, the accuracy with which dolphins leap high to take small fish out of a trainer’s hand provides anecdotal evidence to the contrary.

Such variation can no doubt be explained with reference to the habitats in which individual species have developed. For example, vision is obviously more useful to species inhabiting clear open waters than to those living in murky rivers and flooded plains. Some dolphins, such as the Chinese baiji, for instance, appear to have very limited vision, and the South asian river dolphins are blind, their eyes reduced to slits that probably allow them to sense only the direction and intensity of light.

Although the senses of taste and smell appear to have deteriorated, and vision in water appears to be uncertain, such weaknesses are more than compensated for by cetaceans’ well-developed acoustic sense. Most species are highly vocal, although they vary in the range of sounds they produce, and many forage for food using echolocation. Large baleen whales primarily use lower frequencies and are often limited in how many sounds they use. Notable exceptions are the nearly song-like choruses of bowhead whales in summer and the complex, haunting utterances of the humpback whales. Toothed species, in general, employ more of the frequency spectrum, and produce a wider variety of sounds than baleen species (though the sperm whale apparently produces a monotonous series of high-energy clicks and little else). Some of the more complicated sounds are clearly communicative, although what role they may play in the social life and ‘culture’ of cetaceans has been more the subject of wild speculation than of solid science.

Reading Passage Vocabulary
Senses of Whales

Some of the senses that we and other terrestrial mammals take for granted are either reduced, absent, or fail to function well in cetaceans, a group of aquatic mammals which include whales. For example, it appears from their brain structure that toothed species are unable to smell. Baleen species, on the other hand, appear to have some related brain structures, but it is not known whether these are functional. It has been speculated that, as the blowholes evolved and migrated to the top of the head, the neural pathways serving a sense of smell may nearly all have been sacrificed. Similarly, although at least some cetaceans have taste buds, the nerves which serve this function are either underdeveloped or rudimentary.

The cetaceans’ sense of touch has also sometimes been described as weak, but this view is probably mistaken. Trainers of captive dolphins and small whales often remark on their animals’ responsiveness to being touched or rubbed, and both captive and free-ranging cetacean individuals of all species (particularly adults and calves, or members of the same subgroup) appear to make frequent contact. This contact may help to maintain order within a group, and stroking or touching are part of the courtship ritual in most species. The area around the blowhole is also particularly sensitive and captive animals often react very strongly to being touched there.

Vision in cetaceans has developed to be more sensitive in different species. When baleen whale species studied in close quarters underwater, specifically a grey whale calf in captivity for a year, and free-range right whales and humpback whales studied and filmed off Argentina and Hawaii, have obviously tracked objects with vision underwater, and they can apparently see moderately well both in water and in the air. However, the position of the eyes in baleen whale restricts the field of vision to the point that they probably do not have the ability to see stereoscopically like humans do, using both eyes.

On the other hand, the position of the eyes in most dolphins and porpoises suggests that they have stereoscopic vision forward and downward. Eye position in freshwater dolphins, who often swim on their side or upside down while feeding, suggests that what vision they have is stereoscopic forward and upward. By comparison, the bottlenose dolphin has extremely keen vision in water. Judging from the way it watches and tracks airborne flying fish, it can apparently see fairly well through the surface of the water as well. And although preliminary experimental evidence suggests that their in-air vision is poor, the accuracy with which dolphins leap high to take small fish out of a trainer’s hand provides anecdotal evidence to the contrary.

Such variation can no doubt be explained with reference to the habitats in which individual species have developed. For example, vision is obviously more useful to species inhabiting clear open waters than to those living in murky rivers and flooded plains. Some dolphins, such as the Chinese baiji, for instance, appear to have very limited vision, and the South asian river dolphins are blind, their eyes reduced to slits that probably allow them to sense only the direction and intensity of light.

Although the senses of taste and smell appear to have deteriorated, and vision in water appears to be uncertain, such weaknesses are more than compensated for by cetaceans’ well-developed acoustic sense. Most species are highly vocal, although they vary in the range of sounds they produce, and many forage for food using echolocation. Large baleen whales primarily use lower frequencies and are often limited in how many sounds they use. Notable exceptions are the nearly song-like choruses of bowhead whales in summer and the complex, haunting utterances of the humpback whales. Toothed species, in general, employ more of the frequency spectrum, and produce a wider variety of sounds than baleen species (though the sperm whale apparently produces a monotonous series of high-energy clicks and little else). Some of the more complicated sounds are clearly communicative, although what role they may play in the social life and ‘culture’ of cetaceans has been more the subject of wild speculation than of solid science.

 
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