Which is characteristic feature of echinodermata ?

Options

A. Canal system
B. Radial symmetry
C. Porous body
D. Ambulacral system

Answer

### Step-by-Step Solution:

1. **Understanding Echinodermata**:
- Echinodermata is a phylum of marine animals that includes starfish, sea urchins, and sea cucumbers. They are known for their unique body structure and functions.

2. **Identifying the Options**:
- The options given are:
- A) Canal system
- B) Radial symmetry
- C) Porous body
- D) Ambulacral system

3. **Analyzing Each Option**:
- **Canal System**: This feature is characteristic of sponges, not echinoderms.
- **Radial Symmetry**: While echinoderms exhibit radial symmetry, this trait is not unique to them as other organisms also display this symmetry.
- **Porous Body**: This is a feature of sponges, which have a porous structure for filtering water.
- **Ambulacral System**: This is a unique feature of echinoderms, also known as the water vascular system. It is essential for their locomotion, feeding, and waste transport.

4. **Conclusion**:
- The characteristic feature of Echinodermata is the **ambulacral system** (water vascular system). Therefore, the correct answer is option D.

### Final Answer:
- The characteristic feature of Echinodermata is the **ambulacral system**.

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