Ink-gland is absent in

Options

A. Loligo
B. Sepia
C. Octopus
D. Nautilus

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which organism does not have an ink gland. The options provided are loligo, sepia, octopus, and nautilus.

2. **Identifying the Organisms**:
- **Loligo**: This is a genus of squids, which are known to have an ink gland.
- **Sepia**: Commonly known as cuttlefish, sepia also possesses an ink gland.
- **Octopus**: Known as devil fish, octopuses have an ink gland as well.
- **Nautilus**: This is a marine cephalopod that is characterized by its external shell.

3. **Classifying the Organisms**: All the mentioned organisms belong to the phylum Mollusca and the class Cephalopoda. However, not all cephalopods have an ink gland.

4. **Analyzing the Presence of Ink Gland**:
- The ink gland is a defensive mechanism found in many cephalopods, allowing them to eject ink to escape from predators.
- While loligo, sepia, and octopus all have this gland, nautilus does not.

5. **Conclusion**: Based on the analysis, the organism that lacks an ink gland is **Nautilus**.

**Final Answer**: The ink gland is absent in **Nautilus** (Option 4).

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