Name the shelled protozoan

Options

A. Elphidium
B. Noctiluca
C. Trichonympha
D. Giardia.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the name of a shelled protozoan. Shelled protozoans are typically characterized by having a protective outer shell or test.

2. **Identifying Options**: The options provided include:
- Elphidium
- Noctiluca
- Trichonympha
- Giardia

3. **Analyzing Each Option**:
- **Elphidium**: This is a genus of foraminifera, which are known for their shell (test). The complete name is Elphidium crispum. This organism is indeed a shelled protozoan.
- **Noctiluca**: This is a dinoflagellate and does not have a shell. It is primarily photosynthetic and does not fit the criteria of a shelled protozoan.
- **Trichonympha**: This organism lives in the gut of termites and does not have a shell. It is involved in a symbiotic relationship with termites, aiding in wood digestion.
- **Giardia**: This is a parasitic protozoan that causes gastrointestinal illness in humans. It does not possess a shell.

4. **Conclusion**: Based on the analysis, the only organism that qualifies as a shelled protozoan is **Elphidium**.

5. **Final Answer**: The shelled protozoan is **Elphidium**.

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