Nautilus occurs in its shell in

Options

A. First chamber
B. All chambers
C. Last chamber
D. partly in first chamber and partly outside

Answer

To solve the question "Nautilus occurs in its shell in", we will analyze the characteristics of Nautilus and its shell structure step by step.

### Step-by-Step Solution:

1. **Understanding Nautilus**:
- Nautilus is a marine cephalopod known for its distinctive external shell. It is one of the most ancient cephalopods still in existence today.

**Hint**: Remember that Nautilus is a cephalopod with an external shell, unlike most other cephalopods.

2. **Shell Structure**:
- The shell of Nautilus is multi-chambered and spirally coiled. Each chamber serves a specific purpose in buoyancy and movement.

**Hint**: Focus on the fact that the Nautilus shell is not just a single chamber but consists of multiple chambers.

3. **Chamber Functionality**:
- As Nautilus grows, it adds new chambers to its shell. However, it only occupies the last chamber, while the other chambers are filled with gas to help with buoyancy.

**Hint**: Consider how Nautilus uses its shell for buoyancy and swimming. This will help you understand where it resides.

4. **Identifying the Correct Option**:
- Given the options:
- First chamber
- All chambers
- Last chamber
- Partially in first chamber and partially outside
- The correct answer is that Nautilus occurs in its shell in the **last chamber**.

**Hint**: Recall that Nautilus only occupies the last chamber of its shell, which is crucial for its buoyancy and movement.

5. **Conclusion**:
- Therefore, the correct answer to the question is that Nautilus occurs in its shell in the **last chamber**.

### Final Answer:
Nautilus occurs in its shell in the **last chamber**.