In Pheretima, locomotion occurs with the help of

Options

A. Circular muscles
B. Longitudinal muscles and setae
C. Circular, longitudinal muscles and setae
D. Parapodia

Answer

**Step-by-Step Solution:**

1. **Identify the Organism**: The question refers to "Pheretima," which is commonly known as the earthworm. It belongs to the phylum Annelida.

2. **Understand Locomotion in Earthworms**: Earthworms are known for their unique method of locomotion, which involves the use of muscles and structures that assist in movement through soil.

3. **Muscle Types Involved**: There are two main types of muscles involved in the locomotion of earthworms:
- **Circular Muscles**: These muscles encircle the body of the earthworm. When they contract, they cause the body to elongate and narrow.
- **Longitudinal Muscles**: These muscles run along the length of the body. When they contract, they shorten the body and help in pulling it forward.

4. **Role of Setae**: In addition to the muscles, earthworms have small bristle-like structures called setae. These setae anchor the worm to the soil, providing grip and stability as it moves.

5. **Movement Process**: The locomotion process involves:
- The earthworm extends its body by contracting the circular muscles.
- It anchors the front part of its body using setae.
- The longitudinal muscles then contract to pull the rest of the body forward.

6. **Final Answer**: Therefore, locomotion in Pheretima (earthworm) occurs with the help of circular muscles, longitudinal muscles, and setae.

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