Crocodylus Niloticus - IELTS Listening Answers & Explanations
From IELTS Recent Actual Test 1 Academic Listening Test 6 · Part 4 · Questions 31–40
Audio
Questions
Questions 31–35 Multiple Choice (One Answer)
Choose the correct letter, A, B, or C.
Questions 36–40 Sentence Completion
Complete the sentences below.
Write NO MORE THAN TWO WORDS AND / OR A NUMBER for each answer.
- Desert crocodiles sometimes live in places with dry periods that last up to 36 months.
- A hole dug by a female crocodile in which to lay eggs can have a 37 of up to 60cm.
- Local people do not 38 crocodiles.
- Crocodiles 39 out of fear when humans populate their habitat.
- Researchers want to study more about population size, 40, and relations to other populations of crocodiles.
Answers & Explanations Summary
| # | Answer | Evidence | Explanation |
|---|---|---|---|
| Q31 | B | This student noticed that on the map displaying the distribution of crocodiles across Africa, there were no crocodiles in the Northern Region, and found no mention in the literature of the existence of crocodiles in the North of Africa | Excerpt/Transcript Explanation: The transcript explains that the student looked at a map and read various academic books but did not see any evidence or records of crocodiles in the North of Africa. Answer Explanation: The answer means that the student did not find any written information in books or research papers about crocodiles living in North Africa. Reason For Correctness: The correct answer is B because the transcript describes a student who checked two sources: a map and the literature. 'Literature' in this context refers to scientific books or articles. Because the student could not find any written mention of crocodiles in that area, they concluded that crocodiles did not live there. Key phrases to note are 'found no mention', which means something was not talked about, and 'literature', which means professional written works. |
| Q32 | A | conducted a survey of the wetlands in Mauritania and received reports of 46 crocodiles living in one group, or float as we say when referring to crocodiles, though the usual number is a little less than half of that | Excerpt/Transcript Explanation: The transcript states that although a group of 46 was reported once, the common group size is usually a bit less than half of that number (half of 46 is 23, so around 20). Answer Explanation: The answer means that crocodiles typically stay together in groups of approximately 20. Reason For Correctness: The correct answer is A because the teacher explains that while one specific report mentioned 46 crocodiles in a group (which is called a 'float'), the normal or typical amount is slightly less than half of 46. Half of 46 is 23, and 20 is the choice that is 'a little less' than that number. Keywords to notice include 'float' (the word for a group of crocodiles), 'usual number' (what is normal), and 'half' (divided by two). |
| Q33 | C | In general, crocodiles are more highly concentrated in wet, subtropical environments near bodies of water and rich vegetation | Excerpt/Transcript Explanation: The transcript explains that these animals are usually found in areas that have plenty of water and a warm climate (subtropical), often close to lakes or rivers with many plants. Answer Explanation: The answer means that African crocodiles usually stay in places that are warm and have a lot of water. Reason For Correctness: The correct answer is C because the text says that crocodiles are mostly found in places that are wet and subtropical. 'Wet' matches the 'wet' in the answer, and 'subtropical' means a climate that is generally warm. The text also mentions they like to be near bodies of water and plants, which fits 'wet climates.' |
| Q34 | A | To utilise every bit of rainfall, these desert crocodiles dig underground caves that collect runoff, thus staying cool and hydrated | Excerpt/Transcript Explanation: The transcript explains that crocodiles in the desert make caves under the ground to keep cool and catch rainwater so they have enough water to drink. Answer Explanation: The answer means that crocodiles living in dry places build their homes below the surface of the earth. Reason For Correctness: The correct answer is A because the transcript says that desert crocodiles dig caves below the ground. These caves help them collect rainwater and stay cool when the weather is very hot and dry. Keywords like "underground" and "dig" show that these homes are under the surface of the earth, not in mountains or just under the water. |
| Q35 | C | The key to this migration is that the Sahara Desert did not always cover the North of Africa. About 8,000 years ago, the land was fertile wetlands perfect for breeding crocodiles. Over time, though, the area dried out and the wetland slowly turned to desert, leading the African crocodile to migrate south to the marshlands they call home today | Excerpt/Transcript Explanation: The transcript says that North Africa used to be a wet place where crocodiles liked to live. However, the land became dry over a long time and turned into a desert. This change made the crocodiles move to a different area. Answer Explanation: The answer says that North Africa had a lot of water and green plants a long time ago, but it slowly became a very dry desert. Reason For Correctness: The correct answer is 'C' because the teacher explains that North Africa was not always a dry desert. Thousands of years ago, the land was a 'wetland,' which is a place with lots of water. Because the area 'dried out' and became a 'desert' over time, the crocodiles had to 'migrate' (move to a new place) to find the water they need to live. |
| Q36 | 8 / eight | In Mauritania, some crocodiles have learned to survive in an area where they can go up to 8 months with no water by spending the driest of times in what's called a torpor, or short period of hibernation | Excerpt/Transcript Explanation: The transcript states that some crocodiles in Mauritania can survive for as long as 8 months without water by sleeping during the driest times. Answer Explanation: The answer 8 is the number of months that desert crocodiles can live without water during dry periods. Reason For Correctness: The correct answer is 8 because the speaker explains that in Mauritania, some crocodiles have learned to survive in areas where there is no water for as long as 8 months. They do this by going into a type of hibernation called torpor. |
| Q37 | depth | Afterwards, the female digs a hole up to 60cm in depth to store the eggs for an 80-day incubation period | Excerpt/Transcript Explanation: The transcript explains that after mating, the female crocodile makes a hole 60 centimeters deep to keep her eggs inside for 80 days. Answer Explanation: The answer "depth" refers to the distance from the top of the hole to its bottom. Reason For Correctness: The correct answer is depth because the speaker mentions that female crocodiles dig holes for their eggs, and these holes can be 60cm deep. The transcript uses the word 'depth' to describe this measurement, which completes the sentence perfectly. |
| Q38 | fear | Although these vicious creatures have attacked humans on a few occasions, the residents are not afraid of them | Excerpt/Transcript Explanation: The transcript explains that even though the crocodiles have sometimes hurt people, the people who live in the same area do not feel scared of these animals. Answer Explanation: The answer "fear" means that the local people who live near the crocodiles are not scared of them. Reason For Correctness: The correct answer is "fear" because the lecturer states that the residents are "not afraid" of the crocodiles. In English, "to fear" something is a verb that means to be afraid of it. Identifying the synonym "not afraid" helps confirm that the missing word in the sentence is "fear." Despite the crocodiles' dangerous reputation, the local people respect them instead of feeling scared. |
| Q39 | attack | They attack when humans populate the crocodiles' habitat, instilling fear and uneasiness in the crocs | Excerpt/Transcript Explanation: The transcript states that crocodiles act aggressively when humans move into their home because it makes the crocodiles feel afraid and uncomfortable. Answer Explanation: The answer "attack" means that crocodiles may use force to try to hurt people. Reason For Correctness: The correct answer is "attack" because the text explains that crocodiles usually do not hunt humans. However, if people move into the crocodiles' living area, the animals can become scared or nervous. In these situations, they will strike out or use force against the people to protect themselves. |
| Q40 | migration patterns | There is still also much to learn about migration patterns, and relations to other populations of crocodiles now found in other parts of the world | Excerpt/Transcript Explanation: The transcript says that scientists still need to find out more about how crocodiles move between different places and how they are connected to other crocodile groups globally. Answer Explanation: The answer means the routes and habits animals follow when they move from one area to another, often to find better living conditions. Reason For Correctness: The correct answer is migration patterns because the professor explains that researchers have several things they still need to study. Among these topics, the professor specifically mentions that there is much to learn about 'migration patterns' alongside population size and how different groups of crocodiles are related to each other. |
Transcript
Good morning. Today, we will continue our study of Crocodylus niloticus by talking about its living habits. We've already discussed the evolutionary attributes that set it apart from its crocodile relatives. Does everyone remember that?
Yes, it has an extremely narrow snout, and three or four rows of protective scales on its back, as compared to two rows on other members of the Crocodylus genus.
Let's take a look at how these carnivorous man-eaters live, where they live, and finally, whether they really deserve their vicious reputation.
To start, I'd like to address a great question posed to me by a student during yesterday's office hours. We talked about the distribution of crocodiles in Africa and saw that they are highly concentrated in the South and West of the continent. This student noticed that on the map displaying the distribution of crocodiles across Africa, there were no crocodiles in the Northern Region, and found no mention in the literature of the existence of crocodiles in the North of Africa. Why might there be no crocodiles in North Africa? Let's save this question for later in the lecture.
To find out more about the social habits of the African crocodile, one researcher named Tara Shine of the University of Ulster in Northern Ireland conducted a survey of the wetlands in Mauritania and received reports of 46 crocodiles living in one group, or float as we say when referring to crocodiles, though the usual number is a little less than half of that.
In general, crocodiles are more highly concentrated in wet, subtropical environments near bodies of water and rich vegetation. While South American crocodiles thrive in cool rainforests, the African crocodile is more equipped for heat. Though they can survive at the hot temperatures found in some deserts, they are not equipped to handle dry climates and thus cannot survive in places like the Sahara Desert of North Africa. As cold-blooded animals, crocodiles' core temperatures fluctuate from their average of 38 degrees Celsius as external conditions change, thus they need to avoid extreme temperatures. Others live an underwater life, keeping a body temperature close to that of the water. As their own unique method of regulating their body temperatures, some African crocodiles have made dens by digging holes in the ground to provide themselves with a cool, dark place to retreat from the hot African sun.
Speaking of the hot African sun, let's go back to the question asked at the beginning of the lecture. We know that there used to be crocodiles in Northern Africa, yet today there are none. What are some possible explanations for this?
Some students have suggested that the African crocodile has evolved from a desert creature into a wetland creature, thus causing them to migrate south for more appropriate condition. Others presume that the crocodile was hunted out of Northern Africa by a fiercer predator. While these are intelligent guesses, the real story is a little bit different.
The key to this migration is that the Sahara Desert did not always cover the North of Africa. About 8,000 years ago, the land was fertile wetlands perfect for breeding crocodiles. Over time, though, the area dried out and the wetland slowly turned to desert, leading the African crocodile to migrate south to the marshlands they call home today.
Some crocodiles did, however, adapt to living in dry conditions. In Mauritania, some crocodiles have learned to survive in an area where they can go up to 8 months with no water by spending the driest of times in what's called a torpor, or short period of hibernation. To utilise every bit of rainfall, these desert crocodiles dig underground caves that collect runoff, thus staying cool and hydrated.
During the mating period in November and December, males attract females to their viciously protected territory through a number of behaviours that range from snapping their jaws all the way to sending infrasonic pulses through the water. Afterwards, the female digs a hole up to 60cm in depth to store the eggs for an 80-day incubation period. The female protects these eggs during the period, and sometimes even helps crack the eggs with her snout at the end.
These teeth-gnashing carnivores are softer than we think. Although these vicious creatures have attacked humans on a few occasions, the residents are not afraid of them. In fact, they show a great deal of reverence towards these wondrous creatures. Some say that crocodiles bring water to their habitat, so if they leave, they will bring the water with them. Obviously this is not true, but it demonstrates the admiration the inhabiting people have for crocodiles.
Generally, crocodiles do not predate on humans. They attack when humans populate the crocodiles' habitat, instilling fear and uneasiness in the crocs. Like any other species, crocodiles are known to attack when feeling fear.
There's still a lot more to be discovered about the African crocodile. Researchers want to know more about the population size, how many crocodiles inhabit Africa in all, how they form separate floats, etc.
There is still also much to learn about migration patterns, and relations to other populations of crocodiles now found in other parts of the world.
Next time, we'll examine a few specific case studies of crocodile populations in Southern Africa.