Pila respires by

Options

A. ctendia
B. pulmonary sac
C. mantle
D. all of these

Answer

**Step-by-Step Solution:**

1. **Identify the Organism**: The organism in question is Pila, commonly known as the apple snail or pond snail. It belongs to the class of gastropod mollusks.

2. **Understand the Respiratory Mechanism**: Pila is known for having a dual mode of respiration, similar to amphibians. This means it can respire both in water and on land.

3. **Aquatic Respiration**: When Pila is in an aquatic environment, it absorbs oxygen directly from the water. This is its mode of respiration when submerged.

4. **Terrestrial Respiration**: When Pila is on land, it needs to utilize atmospheric oxygen. For this purpose, it has a specialized structure called the pulmonary sac.

5. **Structure of the Pulmonary Sac**: The pulmonary sac is located in the mantle cavity and has an opening on the roof of the mantle. This allows air to enter the sac.

6. **Vascularization**: The dorsal walls of the pulmonary sac are highly vascularized, meaning they have a rich supply of blood vessels. This vascularization facilitates efficient gas exchange.

7. **Conclusion**: Therefore, Pila primarily respires through the pulmonary sac when on land, while it absorbs oxygen from water when aquatic.

**Final Answer**: Pila respires by the pulmonary sac.

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