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:
“When a woman drinks it’s as if an animal were drinking, or a child. Alcoholism is scandalous in a woman, and a female alcoholic is rare, a serious matter. It’s a slur on the divine in our nature.”
—Marguerite Duras (b. 1914)
“Come into animal presence.
No man is so guileless as
the serpent. The lonely white
rabbit on the roof is a star
twitching its ears at the rain.”
—Denise Levertov (b. 1923)
“‘Tis said that courage is common, but the immense esteem in which it is held proves it to be rare. Animal resistance, the instinct of the male animal when cornered, is no doubt common; but the pure article, courage with eyes, courage with conduct, self-possession at the cannon’s mouth, cheerfulness in lonely adherence to the right, is the endowment of elevated characters.”
—Ralph Waldo Emerson (1803–1882)