Which type of nephridia open are devoid of nephrotome :

Options

A. Integumentary nephridia
B. Septal nephridia
C. Pharyngeal nephridia
D. Both (2) and (3)

Answer

To answer the question "Which type of nephridia are devoid of nephrostome?" we will analyze the options provided and determine which one fits the criteria.

### Step-by-Step Solution:

1. **Understand the Terms**:
- **Nephridia**: These are excretory organs found in some invertebrates, including earthworms.
- **Nephrostome**: This is a funnel-like opening in some types of nephridia that allows waste to enter from the body cavity into the nephridia.

2. **Evaluate the Options**:
- **Option 1: Integumentary Nephridia**:
- These nephridia are attached to the inner surface of the body wall and discharge waste through nephrostomes. Therefore, they **do have nephrostomes**. This option is incorrect.

- **Option 2: Septal Nephridia**:
- Septal nephridia open into the intestine and also have nephrostomes through which waste enters. Thus, they also **have nephrostomes**. This option is incorrect.

- **Option 3: Pharyngeal Nephridia**:
- Pharyngeal nephridia are similar in structure to septal nephridia but lack nephrostomes. Instead, they have straight and spirally twisted lobes. Therefore, they are **devoid of nephrostomes**. This option is correct.

- **Option 4: Both 2 and 3**:
- Since option 2 is incorrect, this option is also incorrect.

3. **Conclusion**:
- The correct answer is **Option 3: Pharyngeal Nephridia** are open and devoid of nephrostome.

### Final Answer:
Pharyngeal nephridia are the type of nephridia that are open and devoid of nephrostome.

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