Which of the following is not a characteristic feature of phylum aschelminthes?

Options

A. Bilaterally symetrical,triploblastic animals
B. Pseudocoelomate animals and unsegmented animals
C. Incomplete alimentary canal
D. They are dioecious

Explanation

To determine which characteristic is not a feature of the phylum Aschelminthes, we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Aschelminthes**:
- Aschelminthes, also known as nematodes or roundworms, are a diverse group of organisms. They are characterized by specific features that distinguish them from other phyla.

2. **Evaluating the Options**:
- **Option 1: Bilateral Symmetry and Triploblastic Animals**:
- Aschelminthes exhibit bilateral symmetry and are triploblastic, meaning they have three germ layers (ectoderm, mesoderm, and endoderm). This is a characteristic feature of the phylum.
- **Conclusion**: This option is a characteristic feature of Aschelminthes.

- **Option 2: Pseudocoelomate and Unsegmented Animals**:
- Members of Aschelminthes are pseudocoelomate, meaning they have a body cavity that is not fully lined with mesoderm. They are also unsegmented.
- **Conclusion**: This option is also a characteristic feature of Aschelminthes.

- **Option 3: Incomplete Alimentary Canal**:
- An incomplete alimentary canal refers to a digestive system that has only one opening (mouth), which is a characteristic of the phylum Platyhelminthes (flatworms), not Aschelminthes. Aschelminthes have a complete digestive system with a mouth and an anus.
- **Conclusion**: This option is NOT a characteristic feature of Aschelminthes.

- **Option 4: Dioecious**:
- Aschelminthes are dioecious, meaning they have separate male and female individuals. This is indeed a characteristic feature of this phylum.
- **Conclusion**: This option is a characteristic feature of Aschelminthes.

3. **Final Answer**:
- Based on the evaluation, the option that is NOT a characteristic feature of phylum Aschelminthes is **Option 3: Incomplete Alimentary Canal**.