Which one of the following is NOT a characteristic of phylum Annelida

Options

A. Pseudocoelom
B. Ventral nerve cord
C. Closed circulatory system
D. Segmentation

Answer

To determine which of the following is NOT a characteristic of phylum Annelida, let's analyze each option provided:

1. **Pseudocoelom**:
- Annelids are characterized by having a true coelom, which is a body cavity completely lined by mesoderm. A pseudocoelom, on the other hand, is a body cavity that is not completely lined by mesoderm. Therefore, this option is NOT a characteristic of Annelida.

2. **Ventral nerve cord**:
- Annelids possess a well-developed nervous system that includes a ventral nerve cord. This is a characteristic feature of the phylum, indicating that this option is a characteristic of Annelida.

3. **Closed circulatory system**:
- Annelids have a closed circulatory system, meaning that the blood is contained within vessels and does not fill the body cavity. This is another characteristic feature of Annelida.

4. **Segmentation**:
- Annelids exhibit segmentation, which is the division of the body into repeated segments. This is a defining characteristic of the phylum, known as metamerism.

Based on the analysis above, the option that is NOT a characteristic of phylum Annelida is **Pseudocoelom**.

### Step-by-Step Solution:
1. **Identify the characteristics of Annelida**: Understand that Annelids have a true coelom, a ventral nerve cord, a closed circulatory system, and segmentation.
2. **Analyze each option**: Compare each option against the known characteristics of Annelida.
3. **Determine the incorrect option**: Identify that Pseudocoelom does not belong to Annelida as they possess a true coelom.
4. **Conclude the answer**: State that the answer is Pseudocoelom.