Whales and Dolphins Respiration Explained

This question asks us to identify the true statements about how whales and dolphins breathe (respiration).

Analyzing Respiration Statements

Let's look at each statement:

• Statement (A): They cannot use dissolved Oxygen.
  Whales and dolphins are marine mammals. Like humans, they have lungs and breathe air. They cannot extract oxygen that is dissolved in the water the way fish do using gills. They must come to the surface to breathe atmospheric air. Therefore, this statement is true.
• Statement (B): They have gills.
  Gills are respiratory organs found in fish and some other aquatic animals, used to extract dissolved oxygen from water. Since whales and dolphins are mammals, they possess lungs, not gills, for breathing air. Therefore, this statement is false.
• Statement (C): They have large nostrils.
  Whales and dolphins have nostrils, commonly known as 'blowholes', located on the top of their heads. These are adapted for efficient breathing at the water's surface. The size and position allow them to quickly take in air and release stale air and water vapor. Thus, this statement is generally considered true.
• Statement (D): They often come up to the water surface to breathe.
  As air-breathing mammals, whales and dolphins must regularly surface to inhale oxygen and exhale carbon dioxide. Their entire respiratory system is adapted for this, requiring them to ascend periodically. This statement is true.

Conclusion on Respiration Facts

Based on the analysis:

• Statement (A) is true.
• Statement (B) is false.
• Statement (C) is true.
• Statement (D) is true.

The statements that are true in the context of respiration in whales and dolphins are (A), (C), and (D).