In Hydra , cnidobalsts employed during looping are

Options

A. Volvents
B. Stenoteles
C. Atrichous isorhizas
D. Desmonemes.

Answer

To answer the question "In Hydra, cnidoblasts employed during looping are," we will follow these steps:

### Step 1: Understand the Types of Cnidoblasts
Cnidoblasts, also known as cnidocytes, are specialized cells in cnidarians that contain nematocysts (stinging structures). There are different types of cnidoblasts, each serving different functions.

### Step 2: Identify the Relevant Cnidoblasts
The main types of cnidoblasts discussed are:
- **Stenoteles**: The largest type, used for stinging.
- **Holotrichs**: Have a narrow butt and are used for sticking to prey.
- **A-trichs**: Lack a butt and are used for anchoring.
- **Desmonemes**: These are specifically mentioned in relation to looping.

### Step 3: Focus on the Function of Desmonemes
Desmonemes are identified as the cnidoblasts used during the looping movement in Hydra. They have a unique structure:
- They have no butt.
- The thread tube is short, thick, and spineless, forming a single loop that is closed at the tip.

### Step 4: Conclusion
Based on the information, the cnidoblasts employed during looping in Hydra are **Desmonemes**. Therefore, the correct answer is option 4.

### Final Answer
**Desmonemes** are the cnidoblasts employed during looping in Hydra.

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