What is common amongst Earthworm, Cockroach and Centipede?

Options

A. (a) metamerism
B. (b) sexual dimorphism
C. (c) chitinous exoskeleton
D. (d) haemocoel

Answer

To determine what is common amongst Earthworm, Cockroach, and Centipede, we can follow these steps:

### Step 1: Identify the Classification
- **Earthworm** belongs to the phylum **Annelida**.
- **Cockroach** and **Centipede** belong to the phylum **Arthropoda**.

### Step 2: Analyze Common Features
- **Metamerism**: This is the segmentation of the body into linear series.
- Earthworms exhibit metamerism as their bodies are segmented.
- Cockroaches and centipedes also show metamerism, as their bodies are divided into segments.

### Step 3: Evaluate Other Features
- **Sexual Dimorphism**: This refers to the presence of distinct male and female forms.
- This feature is present in cockroaches but not in earthworms or centipedes.

- **Exoskeleton**: This is a hard outer structure that provides support and protection.
- Exoskeletons are present in cockroaches and centipedes but absent in earthworms.

- **Hemocoel**: This is an open blood cavity where blood directly bathes the tissues.
- Hemocoel is present in cockroaches and centipedes but absent in earthworms.

### Step 4: Conclusion
From the analysis, the only feature that is common to all three organisms (Earthworm, Cockroach, and Centipede) is **Metamerism**.

### Final Answer
The common feature amongst Earthworm, Cockroach, and Centipede is **Metamerism**.

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