Nephridia of Pheretima are

Options

A. Protonephridia
B. Solenocytes
C. Micrometanephridia
D. Meganephridia

Answer

**Step-by-Step Solution:**

1. **Understanding Nephridia**: Nephridia are excretory organs found in various invertebrates, including earthworms. They play a crucial role in the excretion of waste and osmoregulation.

2. **Identifying the Type of Nephridia in Pheretima (Earthworm)**: The question specifically asks about the nephridia of Pheretima, which is a genus of earthworms. In earthworms, the primary type of nephridia present is known as integumentary nephridia.

3. **Characteristics of Integumentary Nephridia**:
- These nephridia are also referred to as micrometanephridia or micronephridia.
- They are small and are scattered throughout the internal surface of the earthworm's body wall.
- They are V-shaped structures that hang out in the pilum region of the earthworm.

4. **Distribution and Quantity**:
- Micrometanephridia are absent in the first two segments of the earthworm.
- In each segment (except the clitellar region), there are about 200 to 250 micrometanephridia.
- The clitellar region contains approximately ten times more micrometanephridia than the usual number.

5. **Conclusion**: Based on the characteristics and distribution of nephridia in earthworms, the correct answer to the question is that the nephridia of Pheretima are micrometanephridia.

**Final Answer**: The nephridia of Pheretima are micrometanephridia.

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