What are cetaceans? List of peculiartise of them. Give one example.

Explanation

### Step-by-Step Solution:

1. **Definition of Cetaceans**:
Cetaceans are a group of marine mammals that belong to the order Cetacea. They are primarily adapted to life in water and include animals such as whales, dolphins, and porpoises.

2. **Classification**:
Cetaceans are classified under the class Mammalia, which means they share common characteristics with other mammals, such as having mammary glands for nursing their young.

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