Which of the following is not a chordate characteristics ?

Options

A. Dorsal supporting rod, the notochord
B. Dorsal hollow nerve cord
C. Pharyngeal pouches
D. Vertebral column

Explanation

To solve the question "Which of the following is not a chordate characteristic?" we need to analyze the options provided and identify which one does not apply to all chordates. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand Chordate Characteristics
Chordates are a group of animals that share four key characteristics at some stage of their life cycle:
1. **Notochord**: A dorsal supporting rod that provides structural support.
2. **Dorsal Hollow Nerve Cord**: A nerve cord that runs along the back, which develops into the brain and spinal cord in higher organisms.
3. **Pharyngeal Pouches (or Gill Slits)**: These are present at some stage of development and may develop into gills in aquatic species.
4. **Post-anal Tail**: A tail that extends beyond the anus, which may be reduced in some adult forms.

### Step 2: Analyze the Options
Now, let’s look at the options given in the question:
- **A. Dorsal supporting rod (the notochord)**: This is a characteristic of all chordates.
- **B. Dorsal hollow nerve cord**: This is also a characteristic of all chordates.
- **C. Pharyngeal pouches (or gill slits)**: This is a characteristic found in all chordates.
- **D. Vertebral column**: This is not found in all chordates; it is specific to vertebrates (a subphylum of chordates).

### Step 3: Identify the Correct Answer
Since the question asks for the characteristic that is **not** found in all chordates, we can conclude that:
- The **vertebral column** (option D) is not a characteristic of all chordates, as it is only present in vertebrates and absent in urochordates and cephalochordates.

### Final Answer
Therefore, the answer to the question is **D. Vertebral column**.

---