In fast swimming fishes, propulsion is mainly due to

Options

A. Pelvic fins
B. Caudal fin
C. Dorsal fin
D. Pectroal fins

Answer

To solve the question regarding the propulsion mechanism in fast swimming fishes, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks about the primary fin responsible for propulsion in fast swimming fishes. Propulsion refers to the action of pushing the body forward.

2. **Identify the Types of Fins**:
- **Pelvic Fins**: Also known as ventral fins, these are paired fins located behind the pectoral fins. They help with stabilization but are not the main source of propulsion.
- **Caudal Fin**: This is the tail fin, located at the end of the fish. It is crucial for propulsion as it provides the primary thrust needed for fast swimming.
- **Dorsal Fin**: This fin is located on the back of the fish and helps with stability but does not contribute significantly to propulsion.
- **Pectoral Fins**: These are paired fins located on each side of the fish, often referred to as the fish's arms. They assist in maneuvering but are not the main source of propulsion.

3. **Analyze the Function of Each Fin**:
- The **caudal fin** is designed for powerful strokes that propel the fish forward, making it essential for fast swimming.
- The other fins (pelvic, dorsal, and pectoral) play supportive roles in stabilization and maneuverability but do not primarily provide propulsion.

4. **Conclude the Answer**: Based on the analysis, the fin that primarily provides propulsion in fast swimming fishes is the **caudal fin**.

### Final Answer:
The propulsion in fast swimming fishes is mainly due to the **caudal fin** (Option B).

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