Helically coiled X-organ occurs in
(a) Crustacea
(b) Insecta
(c) Amphibia
(d) Porifera

Options

A. Crustacea
B. Insecta
C. Amphibia
D. Porifera.

Answer

To determine where the helically coiled X-organ occurs, we will analyze the options provided in the question.

### Step-by-Step Solution:

1. **Understanding the X-organ**: The X-organ is a specialized gland that is part of a sinus gland complex. It is responsible for producing various secretions, including hormones that regulate important physiological processes.

2. **Location of the X-organ**: The X-organ is located at the base of the eye stalk in certain organisms. This anatomical feature is crucial for its function.

3. **Functions of the X-organ**: The secretions from the X-organ play significant roles in:
- Influencing molting processes.
- Supporting gonad development.
- Maintaining water balance and glucose levels in the body.

4. **Identifying the correct phylum**:
- **Option (a) Crustacea**: Crustaceans, such as crabs and lobsters, possess the X-organ as part of their endocrine system.
- **Option (b) Insecta**: Insects have different hormonal systems and do not have the X-organ.
- **Option (c) Amphibia**: Amphibians do not possess the X-organ; they have different endocrine glands.
- **Option (d) Porifera**: Sponges (Porifera) lack complex organ systems, including the X-organ.

5. **Conclusion**: Based on the information gathered, the helically coiled X-organ is primarily found in Crustacea.

### Final Answer:
The correct answer is (a) Crustacea.

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