Which of the following is not a feature of species of Phylum Chordata ?

Options

A. Presence of a notochord
B. Presence of pharyngeal gill slits
C. Presence of a ventral, hollow nerve cord
D. Presence of a coelom

Explanation

To determine which of the following is not a feature of species of Phylum Chordata, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Phylum Chordata**:
- Phylum Chordata is characterized by certain features that must be present at some stage of the organism's life cycle, either during embryonic development or in adulthood.

2. **Identifying the Key Features of Chordates**:
- The four main diagnostic characteristics of Chordates are:
- **Presence of Notochord**: A flexible rod-like structure that provides support.
- **Dorsal Hollow Nerve Cord**: A nerve cord that is located on the dorsal side of the organism and is hollow.
- **Pharyngeal Gill Slits**: Openings that appear in the pharynx at some stage of development.
- **Post-anal Tail**: A tail that extends beyond the anus, which may be reduced or absent in some adult forms.

3. **Analyzing the Options**:
- **Option A: Presence of Notochord**: This is a feature of Chordates.
- **Option B: Presence of Pharyngeal Gill Slits**: This is also a feature of Chordates.
- **Option C: Presence of Ventral Hollow Nerve Cord**: This is incorrect as Chordates have a dorsal hollow nerve cord, not a ventral one. Therefore, this is the option that does not belong.
- **Option D: Presence of Coelom**: Chordates possess a true coelom, so this is a feature of Chordates.

4. **Conclusion**:
- The correct answer is **Option C: Presence of Ventral Hollow Nerve Cord**, as it is not a feature of Phylum Chordata.