Dolphins: Intelligence Beneath the Surface
Dolphins have long fascinated scientists because of their apparent intelligence and complex social behaviour. They belong to the family of marine mammals known as cetaceans, which also includes whales and porpoises. More than forty species of dolphins have been identified, inhabiting a variety of marine and freshwater environments.
Many dolphin species live in social groups called pods, which may consist of only a few individuals or several hundred members. These groups are not always stable. In some species, dolphins frequently leave one pod and join another, while others tend to remain with the same companions for extended periods.
Researchers have observed dolphins using a wide range of sounds, including whistles, clicks and burst pulses. Studies indicate that each dolphin develops a distinctive whistle during its early years, which appears to function in a manner similar to a personal name. However, scientists continue to investigate whether dolphins consciously assign these whistles to one another.
Dolphins are also known for their hunting strategies. In certain coastal regions, bottlenose dolphins work together to herd fish into shallow waters, making them easier to catch. Elsewhere, some dolphins have been seen carrying marine sponges on their snouts while searching for food on the seabed. Scientists believe this behaviour protects sensitive skin from injury, although alternative explanations have also been proposed.
Evidence suggests that dolphins possess advanced cognitive abilities. Experiments have shown that they can recognise themselves in mirrors, a skill previously associated mainly with humans and a few other animals. Nevertheless, some researchers argue that mirror recognition alone should not be regarded as definitive proof of self-awareness.
Despite widespread public interest in dolphins, many aspects of their behaviour remain poorly understood. For example, little is known about how dolphins transmit hunting techniques between generations. In recent years, increasing levels of underwater noise produced by ships and industrial activities have raised concerns among conservationists, who fear that such disturbances may interfere with dolphin communication.
Questions 1–12
Do the following statements agree with the information given in the passage?
TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if there is no information about this
Questions
1. All dolphin species inhabit oceans.
2. Some dolphin groups contain hundreds of individuals.
3. Dolphins generally remain with the same pod members throughout their lives.
4. Researchers have confirmed that dolphins intentionally give names to other dolphins.
5. Certain dolphins use tools while searching for food.
6. Scientists unanimously agree that mirror recognition demonstrates self-awareness.
7. Mirror recognition was once believed to occur mainly in humans and a small number of other species.
8. Conservationists are worried that underwater noise might affect dolphins' ability to communicate.
9. Dolphins using marine sponges are found in every coastal region.
10. Scientists know exactly how hunting methods are passed from older dolphins to younger ones.
11. The average lifespan of bottlenose dolphins exceeds forty years.
12. Some dolphin species regularly move from one social group to another.
Summary
This IELTS reading passage explores the intelligence and social behaviour of dolphins. It discusses dolphin species, pod structures, communication through whistles and clicks, cooperative hunting techniques, and the use of marine sponges as tools. The passage also examines evidence of self-recognition, ongoing scientific debates about dolphin cognition, and concerns about the effects of underwater noise on communication. Twelve True, False, and Not Given questions are included to help learners improve their IELTS reading comprehension skills.