Open type circulatory system is present in which phylum?

Answer

To answer the question regarding which phylum has an open type circulatory system, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Circulatory Systems**:
- There are two main types of circulatory systems in animals: open and closed. In an open circulatory system, the blood is not always contained within blood vessels. Instead, it bathes the organs directly in a body cavity called the hemocoel.

2. **Identify the Phyla with Open Circulatory Systems**:
- The two primary phyla that exhibit an open type circulatory system are:
- **Arthropoda**: This phylum includes insects, arachnids, and crustaceans. They have an open circulatory system where the hemolymph (a fluid equivalent to blood) is not confined to vessels but flows freely in the body cavity.
- **Mollusca**: This phylum includes snails, clams, and octopuses. Mollusks also possess an open circulatory system, where their blood (hemolymph) bathes the organs directly.

3. **Conclusion**:
- Therefore, the answer to the question is that the open type circulatory system is present in the phyla **Arthropoda** and **Mollusca**.

### Final Answer:
The open type circulatory system is present in the phyla **Arthropoda** and **Mollusca**.

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