Sexual dimorphism is distinct in :

Options

A. Hydra
B. Earthworm
C. Sponge
D. Cockroach

Answer

**Step-by-Step Solution:**

1. **Understanding Sexual Dimorphism**: Sexual dimorphism refers to the condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs. This can include variations in size, color, shape, and other physical traits.

2. **Analyzing the Options**: The question provides four options: hydra, earthworm, sponge, and cockroach. We need to evaluate which of these organisms exhibits sexual dimorphism.

3. **Evaluating Each Organism**:
- **Hydra**: Generally, hydras do not show significant sexual dimorphism. They reproduce asexually and have similar physical characteristics in both sexes.
- **Earthworm**: Earthworms are hermaphroditic, meaning they possess both male and female reproductive organs, and do not exhibit distinct sexual dimorphism.
- **Sponge**: Sponges also do not show sexual dimorphism as they can have both male and female reproductive structures and do not have distinct physical differences between sexes.
- **Cockroach**: Cockroaches are known for their sexual dimorphism. Male and female cockroaches exhibit distinct differences in size and physical traits. Males are typically thinner with larger eyes, while females have a broader abdomen and an abdominal pouch.

4. **Conclusion**: Based on the analysis, the organism that shows distinct sexual dimorphism is the cockroach.

5. **Final Answer**: Therefore, the correct answer to the question is option number 4: Cockroach.

---