Which one of the following has an open circulatory system ?

Options

A. Pheretima
B. Periplaneta
C. Hirudinaria
D. Octopus

Answer

To determine which organism has an open circulatory system, we need to understand the differences between open and closed circulatory systems.

### Step-by-Step Solution:

1. **Define Open and Closed Circulatory Systems**:
- An **open circulatory system** is characterized by the absence of blood vessels. In this system, the blood (or hemolymph) flows freely within the body cavity and is not confined to vessels. This allows the fluid to mix with the interstitial fluid.
- A **closed circulatory system**, on the other hand, has blood confined within vessels, preventing it from mixing with the interstitial fluid. This system is more efficient for transporting nutrients and oxygen.

2. **Identify the Organisms**:
- The question provides four options, which we need to evaluate:
- **Ferry time (Earthworm)**: Belongs to the phylum Annelida. Earthworms have a closed circulatory system.
- **Ferriplaneta (Cockroach)**: Belongs to the phylum Arthropoda. Cockroaches have an open circulatory system.
- **Herodinaria (Leech)**: Another example from the phylum Annelida. Leeches also have a closed circulatory system.
- **Octopus**: Belongs to the class Cephalopoda. Octopuses have a closed circulatory system.

3. **Analyze the Options**:
- From the analysis:
- Earthworm (Ferry time) - Closed circulatory system
- Cockroach (Ferriplaneta) - Open circulatory system
- Leech (Herodinaria) - Closed circulatory system
- Octopus - Closed circulatory system

4. **Select the Correct Answer**:
- The only organism from the options provided that has an open circulatory system is **Ferriplaneta (Cockroach)**.

### Final Answer:
The organism that has an open circulatory system is **Ferriplaneta (Cockroach)**.