Historical Misclassification: The article explains that historically, whales were considered fish due to their aquatic lifestyle and superficial resemblance to large fish. This classification persisted until more detailed biological studies were conducted.

Biological Classification: Whales are mammals, not fish. They breathe air through lungs, are warm-blooded, nurse their young with milk, and have a different skeletal and muscular structure compared to fish. These characteristics firmly place whales within the mammalian class.

Modern Understanding: With advancements in marine biology and taxonomy, scientists have been able to accurately classify whales as cetaceans, a group of marine mammals which includes dolphins and porpoises. This classification is based on a range of anatomical and physiological traits distinct from those of fish.

Educational Importance: Understanding the correct classification of whales is crucial for educational purposes and for the accurate dissemination of scientific knowledge. It also plays a role in conservation efforts, as the needs and behaviors of mammals differ significantly from those of fish.