Cephalopoda is characterised by

Options

A. Coming together of head and and foot
B. Enlargement of tentacles
C. Presence of siphon
D. All the above

Answer

**Step-by-Step Solution:**

1. **Understanding Cephalopoda**: Cephalopoda is a class within the phylum Mollusca, which includes organisms such as octopuses, squids, and cuttlefish.

2. **Analyzing the Characteristics**:
- **Coming together of head and foot**: In cephalopods, the head and foot are fused together, which is a defining characteristic of this class. This means that the body structure is adapted for a more complex lifestyle.
- **Enlargement of tentacles**: Cephalopods have tentacles or arms that are significantly enlarged compared to other mollusks. For example, octopuses have eight tentacles, while cuttlefish have ten. These tentacles are crucial for capturing prey and for defense.
- **Presence of siphon**: Cephalopods possess a siphon, which is a tube-like structure that allows them to expel water. This expulsion of water is essential for locomotion, as it helps them move quickly through the water.

3. **Conclusion**: Since all the mentioned characteristics are true for cephalopods, the correct answer is that Cephalopoda is characterized by all of the above options.

**Final Answer**: All of the above.

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