The correct option is
D. a mammal.
Explanation of the Correct Answer
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Understanding Mammals: Mammals are a class of animals characterized by several key features, one of which is the presence of hair or fur on their bodies at some stage of their life cycle. This is a defining characteristic of mammals, which distinguishes them from other animal classes.
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Hair as a Feature: The presence of hair is significant because it serves various functions, including insulation, camouflage, and sensory perception. In aquatic mammals, such as seals and otters, hair can also help with buoyancy and temperature regulation.
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Examples of Aquatic Mammals: In the context of a trawler catching an animal with hair, it is likely that the animal could be a marine mammal. Examples include:
- Seals: These animals have a layer of fur that helps keep them warm in cold water.
- Sea Otters: Known for their dense fur, they are also mammals that live in marine environments.
- Dolphins and Whales: While they have less visible hair, they are still classified as mammals and may have some hair follicles.
Why the Other Options Are Incorrect
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A. An amphibian: Amphibians, such as frogs and salamanders, do not have hair. They typically have moist skin that allows for gas exchange and is often used for respiration. The presence of hair would not be consistent with the characteristics of amphibians.
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B. A reptile: Reptiles, including snakes, lizards, and turtles, have scales instead of hair. They are ectothermic (cold-blooded) and rely on external sources of heat to regulate their body temperature. The presence of hair would not fit the biological classification of reptiles.
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C. A shark: Sharks are cartilaginous fish and do not have hair. They have a tough, scaly skin made of dermal denticles, which are more similar to teeth than to hair. Sharks are also ectothermic and have a completely different physiological structure compared to mammals.
Summary of Key Points
- Mammals are characterized by the presence of hair or fur, which serves various functions.
- Aquatic mammals like seals and otters are examples of animals that could be caught by a trawler and have hair.
- Amphibians and reptiles do not have hair; they have different skin structures (moist skin and scales, respectively).
- Sharks are fish and lack hair, having a different type of skin entirely.
Revision Summary
- Mammals are defined by the presence of hair or fur.
- Aquatic mammals, such as seals and otters, can be caught by fishing trawlers.
- Amphibians and reptiles do not have hair; they have moist skin and scales, respectively.
- Sharks are fish and do not possess hair, making them an incorrect option in this context.