Which one does not occur in Earthworm ?

Options

A. septal nephridia
B. macronephridia
C. integumentary nephridia
D. pharyngeal nephridia

Answer

To answer the question "Which one does not occur in Earthworm?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Types of Nephridia**:
- Nephridia are excretory organs in earthworms that help in the removal of waste materials. They are categorized based on their location in the body.

2. **Identify the Types of Nephridia Mentioned**:
- The options provided are:
- Septal Nephridia
- Macronephridia
- Integumentary Nephridia
- Pharyngeal Nephridia

3. **Analyze Each Type**:
- **Septal Nephridia**: Present in earthworms, located between segments (specifically between the 14th and 19th segments).
- **Integumentary Nephridia**: Also present in earthworms, distributed throughout the body, around 200 to 250 pairs in each segment.
- **Pharyngeal Nephridia**: Present near the pharynx and esophagus, helping in excretion, although absent in the first segment.
- **Macronephridia**: This type is not mentioned as being present in earthworms.

4. **Determine the Correct Answer**:
- Since Septal Nephridia, Integumentary Nephridia, and Pharyngeal Nephridia are all present in earthworms, the type that does not occur is **Macronephridia**.

5. **Final Answer**:
- The correct answer is **Macronephridia** (Option B).