Question

Why are whales not grouped in the fishes?

Answer 1

Marine animals are also referred to as aquatic animals which rely on the ocean and other marine ecosystems for their survival. The oceans are the largest ecosystem of all the other ecosystems. Some of the marine animals include whales, seals, sea lions, manatees, porpoises, polar bears, dolphins and sea otters.

Complete answer:
Whales and Fishes are considered as marine animals as well as chordates. But whales are not grouped under the fishes as there are wide differences between them. Whales are categorised to a diverse group of fully aquatic placental marine mammals which belong to a class Mammalia. Meanwhile, fishes are included in the class-Pisces.

The classes between Whales and Fishes differ because,
-Whales, dolphins, porpoises, seals, walruses, and many other marine animals are mammals but fishes do not come under the mammals category.
-Whales are warm-blooded animals, whereas fishes belong to cold-blooded animals.
-Whales breathe air through a pair of lungs, while fishes respire through its gills.
-Whales possess mammary glands, but such mammary glands are not found in fishes.
-Whales contain hearts with four-chambers, while fishes possess only two-chambered hearts.
-Whales have hair (although very little), eyelids and tear ducts but fishes possess scales typically, and don't have hair, eyelids or tear ducts
-Whales possess arm bones, hand bones, and finger bones, do not contain bony fins while arm bones, hand bones, or finger bones are absent in fishes but typically have bony fins.
-Whales are generally developed from other land-dwelling mammals; but fishes are evolved from primitive aquatic fish ancestors.

Note: Whales that belong to the order cetacea, also includes the marine animals such as dolphins and porpoises. Whales are a diverse group of aquatic marine animals that can be classified into two sub-categories namely baleen and toothed whales.
Baleen whales are one of the largest species of whale which is also called whalebone whales. In Baleen whales, the animals possess a comb-like fringe on the upper jaw which is known as a baleen. It is utilized to filter small fish, and plankton.
Toothed whales possess teeth in the form of beak and hunt on fish, squid, other sea creatures, whales and marine mammals. Through echolocation, they are good at sensing their surrounding environment.