Which subphyla are classified under protochordates?

Answer

To answer the question "Which subphyla are classified under protochordates?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Protochordates**:
- Protochordates is an informal category used to describe certain invertebrates that are closely related to vertebrates.

2. **Identifying the Phylum**:
- The group of protochordates is primarily composed of the phylum Hemichordata.

3. **Identifying the Subphyla**:
- Within the phylum Hemichordata, there are two main subphyla:
- **Urochordata**: This subphylum includes organisms commonly known as tunicates or sea squirts.
- **Cephalochordata**: This subphylum includes lancelets, which are small, fish-like organisms.

4. **Conclusion**:
- Therefore, the two subphyla classified under protochordates are **Urochordata** and **Cephalochordata**.

### Final Answer:
The subphyla classified under protochordates are **Urochordata** and **Cephalochordata**.

---