Perforated surface plate of water vascular system is

Options

A. Stone canal
B. Madreporite
C. Ring canal
D. Ossicle.

Answer

To answer the question about the perforated surface plate of the water vascular system in echinoderms, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Water Vascular System**:
- The water vascular system is a unique feature of echinoderms, which are marine animals such as starfish, sea urchins, and sea cucumbers. This system is crucial for locomotion, feeding, and gas exchange.

2. **Identify the Perforated Surface Plate**:
- The question specifically asks about the perforated surface plate of the water vascular system. This plate is essential for regulating the flow of water in and out of the system.

3. **Know the Terminology**:
- The perforated surface plate is commonly referred to as the "madriporite." This term is critical as it distinguishes this structure from other components of the water vascular system.

4. **Function of the Madriporite**:
- The madriporite acts like a trap door, allowing water to enter and exit the water vascular system in a controlled manner. This regulation is vital for the echinoderm's ability to move and function.

5. **Eliminate Incorrect Options**:
- The other options mentioned (Stonkinar, ring canal, and ossicles) are components of the echinoderm anatomy but do not refer to the perforated surface plate.
- **Stonkinar** connects the madriporite to the ring canal.
- **Ring Canal** is a circular structure around the mouth leading to radial canals.
- **Ossicles** are small calcareous elements providing structural support.

6. **Conclusion**:
- Based on the information gathered, the correct answer to the question is the "madriporite."

### Final Answer:
The perforated surface plate of the water vascular system is called the **madriporite**.