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

Options

A. Bilateral symmetry, triploblastic, pseudocoelomate
B. They are possible most abundant amongst the animals
C. The false body cavity allows body wall muscles ad digestive tract muscles to act independently of each other
D. The bodywall has longitudinal muscles, circular muscles and an elastic cuticle.

Explanation

To answer the question "Which of the following is not a characteristic feature of phylum Nemathelminthes?", we will follow these steps:

### Step 1: Understand the Characteristics of Phylum Nemathelminthes
Phylum Nemathelminthes, also known as Nematoda or roundworms, has several defining characteristics:
- They are **triploblastic**, meaning they have three germ layers: ectoderm, mesoderm, and endoderm.
- They exhibit **bilateral symmetry**.
- They are classified as **pseudocoelomates**, which means their body cavity (pseudocoel) is not completely lined by mesoderm.
- Their body is typically **cylindrical** and has a thread-like appearance.
- The body wall consists of an **epidermis**, **longitudinal muscles**, and a **cuticle**.

### Step 2: Analyze the Given Options
Now, we need to evaluate the options provided in the question to identify which one does not belong to the characteristic features of Nemathelminthes.

1. **Bilateral symmetry** - This is a characteristic feature of Nemathelminthes.
2. **Triploblast** - This is also a characteristic feature.
3. **Pseudocoelomate** - This is a defining characteristic of the phylum.
4. **Body wall has longitudinal muscle, circular muscle, and an elastic cuticle** - This statement is incorrect because Nemathelminthes typically only have longitudinal muscles and do not possess circular muscles.

### Step 3: Identify the Incorrect Statement
From the analysis, the statement regarding the body wall having both longitudinal and circular muscles is not true for Nemathelminthes. They only have longitudinal muscles and an elastic cuticle.

### Conclusion
Therefore, the option that is not a characteristic feature of phylum Nemathelminthes is the one that mentions the presence of circular muscles.

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