Pigment haemocyanin occurs in

Options

A. Annelida
B. Echinodermata
C. Insecta
D. Lower chrodata

Answer

To solve the question "Pigment haemocyanin occurs in," we can follow these steps:

### Step-by-Step Solution:

1. **Understand Haemocyanin**:
- Haemocyanin is a type of respiratory pigment that is involved in the transport of oxygen in certain organisms. It is important to note that it is not the same as hemoglobin.

2. **Identify the Organisms**:
- Haemocyanin is primarily found in the blood of two major groups of organisms: molluscs and arthropods.

3. **Color Change**:
- When oxygenated, haemocyanin appears blue, and when deoxygenated, it becomes colorless. This is a key characteristic that helps in identifying the pigment.

4. **Evaluate the Options**:
- The question likely provides multiple-choice options. We need to identify which of these options includes organisms that possess haemocyanin.
- Common options might include:
- Annelida
- Echinodermata
- Arthropoda (which includes Insecta)
- Lower chordates

5. **Select the Correct Answer**:
- Among the options, Arthropoda (which includes insects) is the correct answer as they are known to contain haemocyanin.
- Annelida typically has hemoglobin, and Echinodermata and lower chordates do not contain haemocyanin.

6. **Final Answer**:
- Therefore, the correct answer to the question is **Arthropoda**.