A free swimming urochordate is

Options

A. Herdmania
B. Botryllus
C. Salpa
D. Ciona

Answer

To solve the question "A free swimming urochordate is?", we will analyze the options provided and determine which one is a free-swimming urochordate.

### Step-by-Step Solution:

1. **Understanding Urochordates**:
- Urochordates are a subphylum of protochordates characterized by the presence of a notochord, which is a flexible rod-like structure, during their larval stage. In adult forms, the notochord is usually present only in the tail region.

2. **Identifying Free Swimming vs. Sessile Forms**:
- Free swimming organisms are those that can move freely in the water, while sessile organisms are those that are attached to a substrate (like rocks or the bottom of a water body) and do not move.

3. **Analyzing the Options**:
- **Herdmania**: This is a type of urochordate that is typically sessile.
- **Botrylus**: This is also a sessile urochordate.
- **Salpa**: This is known to be a free-swimming urochordate.
- **Siona**: This is another sessile urochordate.

4. **Conclusion**:
- Among the options given, Salpa is the only free-swimming urochordate. The other options (Herdmania, Botrylus, and Siona) are all sessile.

### Final Answer:
The free swimming urochordate is **Salpa**.

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