Stomach is absent in

Options

A. cyclostomes
B. Labeo
C. both (1) & (2)
D. none of these

Answer

To answer the question "Stomach is absent in which one?", we will analyze the options provided: cyclostomes, labio, both 1 and 2, or none of these.

### Step-by-Step Solution:

1. **Understanding Cyclostomes**:
- Cyclostomes include organisms like lampreys and hagfishes.
- In these organisms, the stomach is either very weakly developed or almost absent.

2. **Understanding Labio**:
- Labio refers to the genus of the freshwater carp, commonly known as rohu.
- In labio, the true stomach is also absent. Instead, the esophagus opens into a swollen sac-like structure known as the intestinal bulb.

3. **Function of the Intestinal Bulb**:
- The intestinal bulb serves as a storage area for food.
- It is important to note that there is an esophageal valve that prevents the regurgitation of digested food from the intestinal bulb back into the esophagus.

4. **Conclusion**:
- Since both cyclostomes and labio do not possess a true stomach, the correct answer to the question is "both 1 and 2".

### Final Answer:
Both 1 and 2 (stomach is absent in both cyclostomes and labio).

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