Notochord occurs all through the length of body and throughout life in

Options

A. Hemichordata
B. Urochordata
C. Cephalochordata
D. Vertebrata

Answer

To solve the question "Notochord occurs all through the length of body and throughout life in," we will analyze the options provided and the characteristics of each group of organisms mentioned.

### Step-by-Step Solution:

1. **Understanding the Notochord**:
- The notochord is a flexible rod-like structure that is present in all chordates at some stage of their life cycle. It provides support and is located along the dorsal side of the body.

2. **Analyzing the Options**:
- **Hemichordata**:
- In hemichordates, the notochord is not present throughout the body or throughout life. It is only present in certain stages and is not a defining feature of this group.
- **Urochordata**:
- In urochordates (also known as tunicates), the notochord is present only during the larval stage and is typically lost in the adult stage. Therefore, this option is incorrect.
- **Cephalochordata**:
- Cephalochordates, such as lancelets, possess a notochord that extends the entire length of their body and remains throughout their life. This is a defining characteristic of this group.
- **Vertebrata**:
- In vertebrates, the notochord is present during the early stages of development but is replaced by the vertebral column (spine) in adults. Thus, this option is also incorrect.

3. **Conclusion**:
- Based on the analysis, the only group where the notochord occurs all through the length of the body and throughout life is **Cephalochordata**.

### Final Answer:
The correct answer is **Cephalochordata**.

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