Open type of circulation occurs in

Options

A. Arthropoda
B. Chordata
C. Vertebrata
D. Annelida

Answer

**Step-by-Step Solution:**

1. **Understanding Circulatory Systems**: Begin by distinguishing between open and closed circulatory systems. In an open circulatory system, the blood is not confined to blood vessels and flows freely through cavities, directly bathing the organs. In contrast, a closed circulatory system has blood contained within vessels, allowing for more efficient transport.

2. **Identifying Organisms**: Recognize that open circulatory systems are primarily found in invertebrates, particularly within the phylum Arthropoda. This includes organisms such as insects, arachnids, and crustaceans.

3. **Analyzing the Options**: Review the provided options:
- **Arthropoda**: Known for having an open circulatory system.
- **Chordata**: This phylum includes vertebrates, which typically have a closed circulatory system.
- **Vertebrata**: A subphylum of Chordata, also characterized by a closed circulatory system.
- **Annelida**: While these are invertebrates, they possess a closed circulatory system, which is atypical for invertebrates.

4. **Selecting the Correct Answer**: Based on the information gathered, the correct answer is **Arthropoda**, as they exhibit an open type of circulation.

5. **Conclusion**: Thus, the open type of circulation occurs in organisms belonging to the phylum **Arthropoda**.

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