The smallest cnidoblast in the body of Hydra is

Options

A. Penetrant
B. Volvent
C. Atrichous isorhiza
D. Holotrichous isorhiza.

Answer

To solve the question regarding the smallest cnidoblast in the body of Hydra, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Terminology**:
- Cnidoblasts, also known as cnidocytes or nematocysts, are specialized cells in cnidarians (like Hydra) that contain stinging structures used for defense and capturing prey.

2. **Identify the Options**:
- The options provided are:
1. Penetrant
2. Volvent
3. Isorhiza
4. Holotrichus
5. Azytrocus

3. **Recall the Types of Nematocysts**:
- Different types of nematocysts serve various functions:
- **Penetrant**: Used for penetrating prey.
- **Volvent**: Used for wrapping around prey.
- **Isorhiza**: Known for its small size and is involved in locomotion.
- **Holotrichus**: Typically larger and used for different functions.
- **Azytrocus**: Less common and not typically referenced in Hydra.

4. **Determine the Smallest Nematocyst**:
- Among the options, **Isorhiza** is recognized as the smallest type of nematocyst present in Hydra. It is specifically adapted for locomotion and is found on the tentacles of Hydra.

5. **Select the Correct Answer**:
- Based on the information gathered, the correct answer is **Isorhiza**.

### Final Answer:
The smallest cnidoblast in the body of Hydra is **Isorhiza**.

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