Question 65 of 782

A trawler on a fishing trip caught a type of animal with hairs on its body. This animal could have been

  • A. An amphibian
  • B. a reptile
  • C. a shark
  • D. a mammal

Correct Answer: D

Explanation
The correct option is D. a mammal. Detailed Explanation:
  1. Understanding the Options:
  2. A. An amphibian: Amphibians are cold-blooded vertebrates that typically have a life cycle involving both aquatic and terrestrial stages. They include frogs, toads, and salamanders. Amphibians do not have hairs; instead, they have moist skin that helps in respiration and hydration.
  3. B. A reptile: Reptiles are also cold-blooded vertebrates, including snakes, lizards, turtles, and crocodiles. They have scales instead of hair. While some reptiles may have a few bristles or spines, they do not possess hair in the way mammals do.
  4. C. A shark: Sharks are cartilaginous fish, belonging to the class Chondrichthyes. They have a tough, sandpaper-like skin covered in tiny scales called dermal denticles, but they do not have hair. Sharks are adapted to life in water and do not have any hair-like structures.
  5. D. A mammal: Mammals are warm-blooded vertebrates characterized by the presence of hair or fur on their bodies and mammary glands that produce milk for their young. This group includes animals such as whales, dolphins, seals, and otters, many of which can be found in marine environments.
  6. Why Option D is Correct:
  7. The presence of hair on the body is a defining characteristic of mammals. Even marine mammals, such as seals and dolphins, have some hair, especially during their early life stages. The presence of hair indicates that the animal is likely a mammal, as no other class of animals (amphibians, reptiles, or sharks) possesses this feature.
  8. Why the Other Options are Incorrect:
  9. Option A (Amphibian): Amphibians do not have hair; they have smooth, moist skin. This option is incorrect because the defining characteristic of hair is absent in amphibians.
  10. Option B (Reptile): Reptiles have scales, not hair. This option is incorrect for the same reason as amphibians; they do not exhibit the hair characteristic.
  11. Option C (Shark): Sharks are fish and do not have hair. They have a different type of skin structure that is adapted for their aquatic environment. This option is incorrect because it does not align with the presence of hair.
Common Pitfalls:
  • Students may confuse the characteristics of different animal classes. Remember that hair is a unique feature of mammals.
  • It’s important to consider the environment and adaptations of animals. While some animals may live in similar habitats (like amphibians and mammals in water), their physiological traits can be very different.
Revision Summary:
  • Mammals are characterized by the presence of hair and mammary glands.
  • Amphibians and reptiles do not have hair; they have moist skin and scales, respectively.
  • Sharks are cartilaginous fish and also lack hair.
  • The presence of hair on an animal indicates it is a mammal, making option D the correct choice.
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