Whales are classified in the class ‘mammalia’ and order Cetacea in the animal kingdom. The term ‘ whale ’ is sometimes used to refer to all cetaceans, which include the sperm whale , killer whale , pilot whale , and beluga whale . On the other hand, fishes are the members of paraphyletic group, which includes all gill-bearing aquatic animals. The word " whale " comes from the Old English hwæl, from Proto-Germanic "hwalaz, from Proto-Indo-European " (s)kwal-o-, meaning "large sea fish ". [3][4] The Proto-Germanic "hwalaz is also the source of Old Saxon hwal, Old Norse hvalr, hvalfiskr, Swedish val, Middle Dutch wal, walvisc, Dutch walvis, Old High German wal, and German Wal. [3] Other archaic English forms include wal, wale, whal, whalle, whaille, wheal, etc. [5] The term " whale " is sometimes used interchangeably with dolphins and ... A whalefish lives in a world without sunlight. This rarely seen deep-sea fish relies on a network of pores to feel vibrations in the water and sense its surroundings. Learn how whales are related to humans and not to sharks, and what characteristics make them mammals. Find out how whales evolved from land animals, how they breathe, feed, and reproduce, and how they are different from fish .
