Protochordates includes

Options

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

Answer

To answer the question "Protochordates include," we can follow these steps:

### Step-by-Step Solution:

1. **Definition of Protochordates**: Protochordates are a group of animals that exhibit some characteristics of chordates but do not possess all the features of true chordates. They are considered to be the early forms or precursors to the more advanced chordates.

2. **Identification of Groups**: The main groups that fall under protochordates are:
- **Urochordates (or Tunicates)**: These organisms are characterized by having a notochord only in their larval stage. An example is the sea squirt (Ascidians).
- **Cephalochordates**: These organisms retain the notochord throughout their life. An example is the lancelet (Branchiostoma).

3. **Exclusion of Other Groups**:
- **Hemicordates**: This group has characteristics that are not fully chordate and thus cannot be classified as protochordates.
- **Vertebrates**: These are advanced chordates that possess a backbone, which is not a characteristic of protochordates.

4. **Conclusion**: Based on the characteristics and classification, protochordates include **Urochordates and Cephalochordates**.

### Final Answer:
Protochordates include **Urochordates and Cephalochordates**.

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