Ophiura is without

Options

A. digestive system
B. water vascular system
C. excretory system
D. larva in development

Answer

**Step-by-Step Solution:**

1. **Identify Ophiura**: Ophiura is a genus of brittle stars, which are marine invertebrates belonging to the phylum Echinodermata.

2. **Understand the Characteristics of Echinodermata**: Members of the phylum Echinodermata, including Ophiura, are characterized by their unique body structure and lack of certain organ systems.

3. **Excretory System in Echinodermata**: It is important to note that Echinoderms, including Ophiura, do not possess a specialized excretory system. Instead, they utilize other means for excretion.

4. **Excretion Mechanism**: In Ophiura, excretion occurs through the water vascular system, which also serves respiratory functions. This means that they do not have a separate organ dedicated to excretion.

5. **Evaluate the Options**: When presented with options regarding what Ophiura lacks, we can analyze:
- Digestive system: Present
- Water vascular system: Present
- Excretory system: Absent
- Larvae and development: Present

6. **Conclusion**: Based on the analysis, the correct answer is that Ophiura is without an excretory system.

**Final Answer**: Ophiura is without an excretory system (Option C).

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