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.
Famous quotes containing the word animal:
“Woman is a vulgar animal from whom man has created an excessively beautiful ideal.”
—Gustave Flaubert (18211880)
“He is blessed who is assured that the animal is dying out in him day by day, and the divine being established.”
—Henry David Thoreau (18171862)
“Is man no more than this? Consider him well. Thou owst the worm no silk, the beast no hide, the sheep no wool, the cat no perfume. Heres three ons are sophisticated. Thou art the thing itself; unaccommodated man is no more than such a poor, bare, forked animal as thou art.”
—William Shakespeare (15641616)