Animal

Animals are a most important group of organisms, classified as the kingdom Animalia or Metazoa. In general they are multi­cellular, responsive to their situation, and feed by consuming other organisms or parts of them. Their body plan becomes fixed as they build up, usually early on in their development as embryos, although some undergo a method of metamorphosis later on.

The word animal comes from the Latin word animal, of which animalia is the plural, and is derived from anima, significance vital breath or soul. In everyday informal usage, the word usually refers to non-human animals. The biological definition of the word refers to all members of the Kingdom Animalia. Therefore, when the word animal is used in a organic context, humans are included. Aristotle separated the living world between animals and plants, and this was followed by Carolus Linnaeus in the first hierarchical classification. Since then biologists have begun emphasizing evolutionary relationships, and so these groups have been controlled somewhat. For instance, microscopic protozoa were to begin with considered animals because they move, but are now treated separately

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