Hemocyanin is a respiratory pigment found in

Options

A. Echinoderm
B. Annelids
C. Insects
D. Architeuthis

Answer

**Step-by-Step Solution:**

1. **Understanding Hemocyanin**: Hemocyanin is a type of respiratory pigment that contains copper. It is used by some animals to transport oxygen in their blood.

2. **Identifying the Groups**: The question provides four options:
- A. Echinoderm
- B. Annelid
- C. Insects
- D. Architeuthis

3. **Analyzing Each Option**:
- **A. Echinoderm**: This group includes sea stars and sea urchins. They do not use hemocyanin as their respiratory pigment.
- **B. Annelid**: Annelids, such as earthworms, primarily use hemoglobin for oxygen transport, not hemocyanin.
- **C. Insects**: Insects typically use hemolymph with hemoglobin or other pigments, but not hemocyanin.
- **D. Architeuthis**: This is a genus of giant squids, which are part of the mollusca phylum. Mollusks, particularly cephalopods, often utilize hemocyanin as their respiratory pigment.

4. **Conclusion**: Based on the analysis, hemocyanin is found in Architeuthis, making the correct answer **D. Architeuthis**.

---