Chordates differ from non - chordates in having

Options

A. Notochord
B. Dorsal hollow nerve cord
C. Pharyngeal gill slits
D. All the above

Answer

To answer the question "Chordates differ from non-chordates in having," we will analyze the key characteristics that distinguish chordates from non-chordates.

### Step-by-Step Solution:

1. **Understanding Chordates**:
- Chordates are a group of animals that possess certain key features at some stage of their development. These features include a notochord, a dorsal hollow nerve cord, pharyngeal gill slits, and a post-anal tail.

2. **Identifying Key Features**:
- **Notochord**: This is a flexible rod-like structure that provides support. It is present in all chordates at some stage of their life cycle.
- **Dorsal Hollow Nerve Cord**: Unlike non-chordates, chordates have a nerve cord that is located on the dorsal side (the back) and is hollow. This structure develops into the central nervous system (the brain and spinal cord) in vertebrates.
- **Pharyngeal Gill Slits**: These are openings in the pharynx that can develop into gills in aquatic chordates or other structures in terrestrial chordates. Non-chordates do not have these structures.

3. **Comparing with Non-Chordates**:
- Non-chordates, such as arthropods and mollusks, lack a notochord and have a ventral solid nerve cord instead of a dorsal hollow nerve cord. Additionally, they do not possess pharyngeal gill slits.

4. **Conclusion**:
- Since chordates possess all three of these defining features (notochord, dorsal hollow nerve cord, and pharyngeal gill slits) while non-chordates do not, the correct answer to the question is "all of the above."

### Final Answer:
Chordates differ from non-chordates in having **all of the above**: notochord, dorsal hollow nerve cord, and pharyngeal gill slits.

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