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:
“Is man no more than this? Consider him well. Thou ow’st the worm no silk, the beast no hide, the sheep no wool, the cat no perfume. Here’s three on’s are sophisticated. Thou art the thing itself; unaccommodated man is no more than such a poor, bare, forked animal as thou art.”
—William Shakespeare (1564–1616)
“The hounding of a dog pursuing a fox or other animal in the horizon may have first suggested the notes of the hunting-horn to alternate with and relieve the lungs of the dog. This natural bugle long resounded in the woods of the ancient world before the horn was invented.”
—Henry David Thoreau (1817–1862)
“Man is the Religious Animal. He is the only Religious Animal. He is the only animal that has the True Religion—several of them.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)