Which of the following set of animals are triploblastic, true coelomates with open type circulatory system ?

Options

A. Earthworm , Cockroach , Nereis
B. Cockroach, Octopus , Leech
C. Mosquito, pheretima , Nereis
D. Cockroach , Leech , pila

Answer

To determine which set of animals are triploblastic, true coelomates with an open type circulatory system, we can analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Understanding the Terms**:
- **Triploblastic**: Animals that have three embryonic layers: ectoderm, mesoderm, and endoderm.
- **True Coelomates**: Animals that possess a true coelom, which is a body cavity lined by mesoderm.
- **Open Circulatory System**: A type of circulatory system where blood is not confined to vessels and flows freely through cavities.

2. **Analyzing Each Option**:
- **Option 1: Earthworm, Cockroach, Nereis**:
- Earthworm: Triploblastic, true coelomate, closed circulatory system.
- Cockroach: Triploblastic, true coelomate, open circulatory system.
- Nereis: Triploblastic, true coelomate, closed circulatory system.
- **Conclusion**: This option does not satisfy the criteria.

- **Option 2: Cockroach, Octopus, Leech**:
- Cockroach: Triploblastic, true coelomate, open circulatory system.
- Octopus: Triploblastic, true coelomate, closed circulatory system.
- Leech: Triploblastic, true coelomate, closed circulatory system.
- **Conclusion**: This option does not satisfy the criteria.

- **Option 3: Mosquito, Ferritima, Nereis**:
- Mosquito: Triploblastic, but pseudocoelomate, open circulatory system.
- Ferritima: Triploblastic, true coelomate, closed circulatory system.
- Nereis: Triploblastic, true coelomate, closed circulatory system.
- **Conclusion**: This option does not satisfy the criteria.

- **Option 4: Cockroach, Leech, and Pyla**:
- Cockroach: Triploblastic, true coelomate, open circulatory system.
- Leech: Triploblastic, true coelomate, closed circulatory system.
- Pyla: Triploblastic, true coelomate, open circulatory system.
- **Conclusion**: This option satisfies the criteria for cockroach and Pyla, but leech has a closed circulatory system.

3. **Final Conclusion**:
- The only animals that fit the criteria of being triploblastic, true coelomates with an open circulatory system are **Cockroach and Pyla**. Therefore, the correct option is **Cockroach, Pyla** as they both have an open circulatory system.