Which of the following is a cephalochordate?

Options

A. Balanoglossus
B. Branchiostoma
C. Herdmania
D. Cliona

Answer

**Step-by-Step Solution:**

1. **Understanding Cephalochordates**: Cephalochordates are a subphylum of the phylum Chordata. They are characterized by the presence of a notochord that extends from the head to the tail throughout their life. This distinguishes them from other chordates.

2. **Identifying Examples**: The question asks for an example of a cephalochordate. One well-known example is *Branchiostoma*, which is commonly referred to as amphioxus.

3. **Analyzing the Options**: The options provided include:
- A) Belanoglossus
- B) Branchiostoma
- C) Hardmania
- D) Leona

4. **Evaluating Each Option**:
- **Belanoglossus**: This organism belongs to the phylum Hemichordata, not Cephalochordata. It has a partially formed notochord.
- **Branchiostoma**: This is the correct answer as it is a classic example of a cephalochordate.
- **Hardmania**: This organism is part of the Chordata but does not specifically belong to the Cephalochordata subphylum.
- **Leona**: This is found in the phylum Porifera, which are invertebrates and not chordates.

5. **Conclusion**: Based on the analysis, the only organism that qualifies as a cephalochordate is *Branchiostoma*.

**Final Answer**: The cephalochordate among the options is **Branchiostoma**.

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