Class of mollusca in which head, tentacles and eyes are not differentiable is

Options

A. Gastropoda
B. Pelecypoda
C. Cephalopoda
D. Both A and B

Answer

To solve the question regarding the class of Mollusca in which the head, tentacles, and eyes are not differentiable, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for a specific class of mollusks where the head, tentacles, and eyes are not clearly distinguishable from each other.

2. **Identify the Classes of Mollusca**: The options given are:
- Gastropoda
- Pelecypoda (also known as Bivalvia)
- Cephalopoda
- Both A and B

3. **Analyze Each Class**:
- **Gastropoda**: This class includes snails and slugs. In gastropods, the head is well-defined, and they have tentacles and eyes that are clearly differentiable.
- **Pelecypoda (Bivalvia)**: This class includes clams, oysters, and scallops. Members of this class do not have a distinct head, and their tentacles and eyes are not well-defined. They have two shells and are laterally compressed.
- **Cephalopoda**: This class includes squids and octopuses. In cephalopods, the head is prominent, and they have well-developed tentacles and eyes that are easily distinguishable.
- **Both A and B**: This option suggests that both Gastropoda and Pelecypoda fit the criteria, which is not correct since Gastropoda has a defined head.

4. **Conclusion**: Based on the analysis, the class of mollusca in which the head, tentacles, and eyes are not differentiable is **Pelecypoda** (Bivalvia).

5. **Final Answer**: The correct answer is **Pelecypoda**.