Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and independently. All animals are also heterotrophs, meaning they must ingest other organisms or their products for sustenance.
Most known animal phyla appeared in the fossil record as marine species during the Cambrian explosion, about 542 million years ago.
Read more about Animal: Etymology, Characteristics, Origin and Fossil Record, Model Organisms, History of Classification, Ethics
Famous quotes containing the word animal:
“Certain anthropologists hold that man, having discovered tools, ceased to evolve biologically. Animals, never having discovered them, continue to fashion drills out of their beaks, oars out of their hind feet, wings out of their forefeet, suits of armor out of their hides, levers out of their horns, saws out of their teeth. Whether this be true or not, all authorities agree that man is the tool-using animal. It sets him off from the rest of the animal kingdom as drastically as does speech.”
—Stuart Chase (1888–1985)
“Nobody can misunderstand a boy like his own mother.... Mothers at present can bring children into the world, but this performance is apt to mark the end of their capacities. They can’t even attend to the elementary animal requirements of their offspring. It is quite surprising how many children survive in spite of their mothers.”
—Norman Douglas (1868–1952)
“You don’t want to be an animal, you want to observe your own animal functions, so as to get a mental thrill out of them. It is all purely secondary—and more decadent than the most hide-bound intellectualism.”
—D.H. (David Herbert)