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From Citizendium, the Citizens' Compendium

Animals
Scientific classification
Domain: Neomura Kingdom: Opisthokonta Subkingdom: Metazoa
Phyla
Calcarea Silicarea Infrakingdom Eumetazoa Placozoa Orthonectida Rhombozoa Ctenophora Cnidaria Bilateria (unranked) Acoelomorpha Myxozoa Chaetognatha Superphylum Deuterostomia Chordata Hemichordata Echinodermata Xenoturbellida Vetulicolia † Superphylum Ecdysozoa Kinorhyncha Loricifera Priapulida Nematoda Nematomorpha Lobopodia † Onychophora Tardigrada Arthropoda Superphylum Platyzoa Platyhelminthes Gastrotricha Rotifera Acanthocephala Gnathostomulida Micrognathozoa Cycliophora Superphylum Lophotrochozoa Sipuncula Hyolitha † Nemertea Phoronida Ectoprocta Bryozoa Entoprocta Brachiopoda Mollusca Annelida Echiura

The word animal comes from the Latin animale, which is derived from anima, meaning "vital breath", and it refers to a class of living things. Animals are eukaryotic, meaning that they are comprised of cells which contain a nucleus. Unlike bacteria, archaea and most protists, they are usually multicellular. Unlike plants and algae, they generally digest food in an internal chamber. They differ from plants, algae, and fungi by lacking cell walls. Most animals can respond to changes in their environment, and most are motile. The animals are descended from choanoflagellates.