Correct Option
The correct option is (a) 1 only.
Explanation
Fish possess specific anatomical and physiological adaptations that enable them to survive and move efficiently in an aquatic environment. These adaptations include body shape, protective coverings, and specialized organs for locomotion and respiration.
Statement-wise Analysis:
- Statement 1 is Correct: The head and tail of a fish are typically narrower than the middle portion of the body, creating a shape that tapers at both ends. This is known as a streamlined shape. This structure reduces water resistance (drag), allowing the fish to move through the water with minimal energy expenditure.
- Statement 2 is Incorrect: Scales are not absent in all fish species. The majority of fish species possess scales that cover their bodies to provide protection and reduce friction. While certain species (such as catfish) may lack scales, the statement that they are absent in "all" species is factually wrong.
- Statement 3 is Incorrect: Fins are primarily used for locomotion, maintaining balance, and changing direction while swimming. Respiration is the function of gills, which are specialized organs designed to extract dissolved oxygen from water.
Key Takeaway:
Fish are adapted to aquatic life through a streamlined body for efficient movement, fins for balance and steering, and gills for respiration. Scales generally serve as a protective outer layer.