What is meant by a streamlined body? Which classes of vertebrates possess such body morphology? Justify that.

Explanation

### Step-by-Step Solution:

1. **Definition of a Streamlined Body**:
A streamlined body refers to a body shape that is elongated and tapered at both ends. This design minimizes resistance or drag when moving through a fluid, such as water or air. The shape allows for smoother movement, reducing friction against the surrounding medium.

2. **Classes of Vertebrates with Streamlined Bodies**:
The primary classes of vertebrates that exhibit a streamlined body morphology are:
- **Fishes**: This includes both marine and freshwater species. They have adapted to their aquatic environments with bodies that reduce drag.
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