In coelenterates `O_2` is carried to various tissue by

Options

A. Blood pigment
B. plasma
C. diffusion through boyd well
D. tracheal tubes

Answer

**Step-by-Step Solution:**

1. **Understanding Coelenterates**: Coelenterates, also known as Cnidarians, include organisms like Hydra, jellyfish, and corals. They are characterized by their simple body structure and lack of complex organs.

2. **Absence of Lungs and Circulatory System**: In coelenterates, there are no lungs or a circulatory system. This is due to their primitive nature and small size, which limits their need for complex respiratory and circulatory mechanisms.

3. **Gas Exchange Mechanism**: Instead of lungs or blood, coelenterates rely on a process called diffusion for gas exchange. Oxygen (O2) is absorbed directly from the surrounding water through their body surface.

4. **Role of Body Walls**: The body walls of coelenterates are thin and permeable, allowing for the efficient diffusion of gases. Oxygen diffuses into the cells while carbon dioxide diffuses out.

5. **Conclusion**: Therefore, in coelenterates, oxygen is carried to various tissues primarily through diffusion across the body walls, rather than through blood or any other circulatory mechanism.

**Final Answer**: In coelenterates, O2 is carried to various tissues by diffusion through body walls.

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