Question

Which one of the following is NOT an ecological adaptation of a typical coldwater fish?

• A. Clinging and burrowing
• B. Reduced power of locomotion
• C. Narrow gill opening
• D. Modified lips for feeding on periphyton

Hint:

Remember that "Coldwater" often implies "Fast-moving water" in fisheries contexts. Any adaptation that makes a fish "lazy" or "weak" in swimming is usually incorrect for such environments.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Coldwater fishes, particularly those inhabiting torrential Himalayan streams or high-altitude lakes, exist in environments characterized by high dissolved oxygen, low temperatures, and often high-velocity water currents. To survive in these habitats, they have evolved specific morphological and physiological adaptations to prevent being swept away and to efficiently feed on the rocky substrates.
Detailed Explanation:
Ecological adaptations of coldwater fishes usually include:
1. Clinging and Burrowing: Many species like Glyptothorax or Garra possess adhesive discs or specialized skin folds on their ventral surface to attach themselves firmly to stones. Burrowing helps in seeking refuge from extreme currents.
2. Narrow Gill Opening: This is an adaptation to regulate water flow and prevent the entry of silt or debris while maintaining efficient respiration in highly oxygenated, fast-moving water.
3. Modified Lips: Fishes like the Snow Trout (Schizothorax) have developed specialized horny coverings on their lips to scrape algae and periphyton from submerged rocks.
4. Locomotion: Contrary to the option, coldwater fishes require enhanced power of locomotion. They possess streamlined, often flattened bodies and muscular peduncles to navigate against strong currents. A "reduced power of locomotion" would be detrimental, as the fish would be unable to maintain its position or move to feeding and breeding grounds in a torrential stream environment.

Step 2: Final Answer:
Therefore, reduced power of locomotion is not an adaptation; rather, high swimming burst capability and streamlined body shapes are the hallmarks of coldwater species.