Polyp form in Cnidaria is -

Options

A. sessile and cylindrical in hydra
B. sessile and umbrella like in Aurelia
C. free living and cylindirical in Aurelia
D. free living and umbrella like in Hydra

Answer

To solve the question regarding the polyp form in Cnidaria, we will analyze each option provided and determine which one correctly describes the polyp form.

### Step-by-Step Solution:

1. **Understanding Polyp Form**:
- The polyp is one of the two main body forms found in Cnidarians, the other being the medusa.
- Polyp forms are generally characterized by being cylindrical and often sessile (attached to a substrate).

2. **Analyzing the Options**:
- **Option A**: Sessile and cylindrical in Hydra.
- Hydra is indeed a genus of Cnidarians that exhibits a polyp form. The polyp of Hydra is cylindrical and is attached to a surface, making this option a strong candidate.

- **Option B**: Sessile and umbrella-like in Aurelia.
- Aurelia, commonly known as the moon jelly, is primarily known for its medusa form, which is umbrella-shaped. This option is incorrect as it describes a medusa, not a polyp.

- **Option C**: Free living and cylindrical in Aurelia.
- Aurelia does not have a polyp stage that is free-living; it primarily exists in the medusa form. This option is also incorrect.

- **Option D**: Free living and umbrella-like in Hydra.
- Hydra does not exhibit a free-living and umbrella-like form; it has a sessile cylindrical form. This option is incorrect.

3. **Conclusion**:
- After analyzing all options, we find that **Option A** is the correct answer, as it accurately describes the polyp form in Cnidaria, specifically in Hydra.

### Final Answer:
The polyp form in Cnidaria is **Option A: Sessile and cylindrical in Hydra**.