The septal and pharyngeal nephridia open into alimentary canal and are of enteronephric type. It is an adaptation for

Options

A. conservation of water
B. conservation of heat
C. regulation of temperature
D. regulation of amino acids

Answer

**Step-by-Step Solution:**

1. **Identify the Structures**: The question mentions septal and pharyngeal nephridia, which are specific types of nephridia found in earthworms.

2. **Understand Nephridia Function**: Nephridia are excretory organs responsible for the removal of waste products from the body. In earthworms, they play a crucial role in excretion.

3. **Types of Nephridia**: There are three types of nephridia in earthworms:
- Septal Nephridia
- Pharyngeal Nephridia
- Integumentary Nephridia

4. **Location of Nephridia**:
- Septal nephridia are found starting from the 15th segment of the earthworm.
- Pharyngeal nephridia are located in the 4th, 5th, and 6th segments.
- Integumentary nephridia are present in all segments except the first two.

5. **Enteronephric Type**: The question specifies that septal and pharyngeal nephridia are of the enteronephric type, meaning they open into the alimentary canal (gut) and discharge waste there.

6. **Purpose of Adaptation**: The adaptation of these nephridia to open into the alimentary canal allows for the conservation and reabsorption of water. This is crucial for maintaining water balance in the organism.

7. **Evaluate Options**: The question likely provides multiple-choice answers. The correct adaptation for the enteronephric type of nephridia is:
- **Conservation of Water** (Correct)
- Other options such as conservation of heat, regulation of temperature, or regulation of amino acids are incorrect.

8. **Conclusion**: Therefore, the adaptation of septal and pharyngeal nephridia opening into the alimentary canal is primarily for the conservation of water.

**Final Answer**: The adaptation is for the conservation of water.

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