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:
“The animal is ignorant of the fact that he knows. The man is aware of the fact that he is ignorant.”
—Victor Hugo (1802–1885)
“Mind and spirit together make up that which separates us from the rest of the animal world, that which enables a man to know the truth and that which enables him to die for the truth.”
—Edith Hamilton (1867–1963)
“The boxer’s ring is the enjoyment of the part of society whose animal nature alone has been developed.”
—Ralph Waldo Emerson (1803–1882)