Structures peculiar to echinoderms are

Options

A. Tube Feet
B. pedicellariae
C. Ambulacral system
D. All the above.

Answer

### Step-by-Step Solution

1. **Identify the Structures Peculiar to Echinoderms**:
Echinoderms are characterized by several unique structures. The question asks for structures that are specific to this phylum.

2. **Tube Feet**:
- Tube feet are tube-like projections found on the oral side of echinoderms.
- They are part of the water vascular system and play a crucial role in locomotion and feeding.
- Example: Starfish (Asteroidea) exhibit tube feet that help them move and capture prey.

3. **Pedicellariae**:
- These are small, stalked structures that resemble tiny pincers.
- Their primary function is defensive; they help keep the surface of the echinoderm clean by removing debris and deterring predators.
- Pedicellariae are particularly well-developed in sea stars and sea urchins.

4. **Amulacral System (Water Vascular System)**:
- This system is unique to echinoderms and consists of a network of fluid-filled canals.
- It is responsible for locomotion, feeding, and gas exchange.
- The water vascular system operates the tube feet, allowing echinoderms to move and manipulate objects.

5. **Conclusion**:
- All the mentioned structures (tube feet, pedicellariae, and the amulacral system) are peculiar features of echinoderms.
- Therefore, the correct answer to the question is that all of the above structures are specific to echinoderms.

### Final Answer:
All of the above structures (tube feet, pedicellariae, and the amulacral system) are peculiar to echinoderms.

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