Which of the following is not a feature of urochordates?

Options

A. Open circulatory system
B. Neural gland as excretory structure
C. Pharyngeal gill slits throughout the life
D. Notochord in adult stage

Answer

To determine which of the following is not a feature of urochordates, we will analyze the characteristics of urochordates and the options provided.

1. **Understanding Urochordates**:
- Urochordates, also known as tunicates, belong to the subphylum Urochordata within the phylum Chordata. They are primarily marine organisms.
- One of the key characteristics of urochordates is that the notochord is present only in the larval stage. In the adult form, the notochord is absent.

2. **Analyzing the Options**:
- **Option A: Open circulatory system**: Urochordates possess an open circulatory system where blood is not confined entirely to vessels.
- **Option B: Neural gland as excretory organ**: Urochordates have a neural gland that functions in excretion.
- **Option C: Pharyngeal gill slit throughout life**: Urochordates retain pharyngeal gill slits throughout their life, which is a characteristic feature of the group.
- **Option D: Notochord in adult stage**: As mentioned earlier, the notochord is only present in the larval stage and is absent in adults.

3. **Conclusion**:
- The statement that is not a feature of urochordates is **Option D: Notochord in adult stage**. This is because the notochord is not present in the adult stage of urochordates.

**Final Answer**: Option D: Notochord in adult stage.

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