select the features which is not applicable to Annelida.

Options

A. Organ system level of organization
B. Closed type of circulatory system
C. Protenephridia for excretion
D. Tube within tube body plan

Answer

To determine which feature is not applicable to Annelida, we need to analyze the characteristics typically associated with this phylum. Here’s a step-by-step solution:

### Step 1: Identify the features of Annelida
Annelida, commonly known as segmented worms, have several key features:
- **Metameric Segmentation**: The body is divided into segments (metameres).
- **Organ System Level of Organization**: They possess a complex organization with specialized organs.
- **Closed Circulatory System**: Blood circulates within vessels, making it a closed system.
- **Nephridia for Excretion**: Annelids use nephridia for excretion, not protonephridia.

### Step 2: Analyze the given features
We need to evaluate the features mentioned in the question:
1. **Organ System Level of Organization**: This is applicable to Annelida.
2. **Closed Type of Circulatory System**: This is also applicable to Annelida.
3. **Protonephridia for Excretion**: This is NOT applicable to Annelida, as they use nephridia instead.
4. **True Digestive System**: Annelida has a complete digestive system with two openings.

### Step 3: Conclusion
The feature that is not applicable to Annelida is **Protonephridia for Excretion**. Annelids utilize nephridia for their excretory processes.

### Final Answer
**Protonephridia for Excretion** is the feature that is not applicable to Annelida.

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