Whales are not fish, they are mammals that live in the ocean.

Cetaceans are typically aquatic animals. Their bodies are streamlined and fish-like. That is why they are often called whales. They are actually mammals that live in the ocean." Whales have the largest and most complex brains of any animal on the planet, "They are social, sensitive animals with strong memories and a strong tendency to take care of their offspring and help others. Whales are also the largest animals in the world. The largest blue whale is 33 meters long and weighs 160 tons.

Whales are born in the womb. They usually give birth to one child per womb and their children are raised by their mother's milk. The fish are oviparous. They can lay thousands of eggs at a time. Once they hatch, the young can live independently without nursing. Whales have a constant body temperature that averages 35.5 degrees Celsius and is maintained in both cold and tropical waters. The body temperature of whales is constant, averaging 35.5 degrees Celsius, and is maintained in both cold and tropical waters. Fish are thermotropic and their body temperature varies with the ambient temperature. Whales breathe with their lungs and often need to surface for air. Fish breathe through their gills, absorbing oxygen dissolved in the water, and remain underwater.

Whales belong to the phylum Chordata, the subphylum Vertebrata, the class Mammalia, the subclass Truorhynchidae, which contains about 98 species of placental mammals that live in the oceans and rivers. There are more than 30 species in Chinese waters. All species of Cetacea inhabit the ocean except for a few species that live in fresh water.

The definition of a whale itself is vague, and the order Cetacea can include all cetaceans, as well as cetaceans of specific families. The order Cetacea also includes all dolphins. Cetacea is divided into two main suborders: baleen whales (Mysticeti) and toothed whales (Odontoceti).

The baleen whales are fewer in number, but they are huge, with the smallest known species measuring more than 6 meters in length, and the world's largest animal, the blue whale, belonging to the baleen whales. However, the toothed whales vary greatly in size, with the smallest species only about 30cm long and the largest sperm whales over 20 meters long. Whales do not belong to the class of fish, but to the class of mammals.