¿Qué es un mamífero?

The video explains why whales are classified as mammals rather than fish. Despite their similar shapes, whales exhibit behaviors and characteristics typical of mammals, such as breathing air through blowholes, giving birth to live young, and nursing them with milk. Unlike fish, whales are warm-blooded and have some hair. These traits led scientists to conclude that whales are mammals.

What new insight or understanding did you gain from this video?