Animal

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:

    To a teacher of languages there comes a time when the world is but a place of many words and man appears a mere talking animal not much more wonderful than a parrot.
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    Henry David Thoreau (1817–1862)