Animal
|image =rect 0 0 118 86 Echinoderm rect 0 86 118 172 Cnidaria rect 0 172 118 258 Tardigrade rect 0 258 118 344 Crustacean rect 0 344 118 430 Arachnid
rect 118 0 236 86 Sponge rect 118 86 236 172 Insect rect 118 172 236 258 Bryozoa rect 118 258 236 344 Acanthocephalan rect 118 344 236 430 Flatworm
rect 236 0 354 86 Mollusc rect 236 86 354 172 Annelid rect 236 172 354 258 Vertebrate rect 236 258 354 344 Tunicate rect 236 344 354 430 Phoronid
Over 1.5 million living animal species have been described, of which around 1.05 million are insects, over 85,000 are molluscs, and around 65,000 are vertebrates. It has been estimated there are as many as 7.77 million animal species on Earth. Animal body lengths range from to . They have complex ecologies and interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology, and the study of animal behaviour is known as ethology.
Most living animal species belong to the infrakingdom Bilateria, a highly proliferative clade whose members have a bilaterally symmetric body plan. The vast majority belong to two large superphyla: the protostomes, which includes organisms such as the arthropods, molluscs, flatworms, annelids and nematodes; and the deuterostomes, which include the echinoderms, hemichordates and chordates, the latter of which contains the vertebrates. The simple Xenacoelomorpha have an uncertain position within Bilateria.
Animals first appear in the fossil record in the late Cryogenian period and diversified in the subsequent Ediacaran. Earlier evidence of animals is still controversial; the sponge-like organism ''Otavia'' has been dated back to the Tonian period at the start of the Neoproterozoic, but its identity as an animal is heavily contested. Nearly all modern animal phyla became clearly established in the fossil record as marine species during the Cambrian explosion, which began around 539 million years ago (Mya), and most classes during the Ordovician radiation 485.4 Mya. 6,331 groups of genes common to all living animals have been identified; these may have arisen from a single common ancestor that lived about 650 Mya during the Cryogenian period.
Historically, Aristotle divided animals into those with blood and those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his ''Systema Naturae'', which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa (now synonymous with Animalia) and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between taxa.
Humans make use of many other animal species for food (including meat, eggs, and dairy products), for materials (such as leather, fur, and wool), as pets and as working animals for transportation, and services. Dogs, the first domesticated animal, have been used in hunting, in security and in warfare, as have horses, pigeons and birds of prey; while other terrestrial and aquatic animals are hunted for sports, trophies or profits. Non-human animals are also an important cultural element of human evolution, having appeared in cave arts and totems since the earliest times, and are frequently featured in mythology, religion, arts, literature, heraldry, politics, and sports. Provided by Wikipedia
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2Texto bibliotecaUBA
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4Texto bibliotecaFAO IT
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6by XIII International Congress on Animal Reproduction 18310, International Congress on Animal Reproduction. 13 (June 30-July 4, 1996 : Sydney. AU) 18311
Published 1996Texto bibliotecaUBA -
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8by Lundbeck 17622, Leo 17623, Symposium on Prostaglandins in Animal Reproduction (1981 : Uppsala. SE) 17624
Published 1981Texto bibliotecaUBA -
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10International Congress on Animal Reproduction and Artificial Insemination. v. 1: Plenary sessions: general reports; v. 2: Round tables: invited guests; v. 3: Symposia: summaries of... International Congress on Animal Reproduction and Artificial Insemination. v. 1: Plenary sessions: general reports; v. 2: Round tables: invited guests; v. 3: Symposia: summaries of...by International Congress on Animal Reproduction and Artificial Insemination eng 16 Jun 1980 9. Madrid (Spain)
Published 1980Texto bibliotecaFAO IT -
11by 10th International Congress on Animal Reproduction and Artificial Insemination 18014, Congreso Internacional de Reproducción Animal e Inseminación Artificial. 10. International Congress on Animal Reproduction and Artificial Insemination (june 10-14, 1984 : IL. US) 18015
Published 1984Texto bibliotecaUBA -
12by 9th International Congress on Animal Reproduction and Artificial Insemination 18301, Congreso Internacional de Reproducción Animal e Inseminación Artificial. 9. International Congress on Animal Reproduction and Artificial Insemination (16-20 June 1980 : Madrid. ES) 18302
Published 1980Texto bibliotecaUBA -
13by 9th International Congress on Animal Reproduction and Artificial Insemination 18301, Congreso Internacional de Reproducción Animal e Inseminación Artificial. 9. International Congress on Animal Reproduction and Artificial Insemination (16-20 June 1980 : Madrid. ES) 18302
Published 1980Texto bibliotecaUBA -
14by International Congress on Animal Reproduction and Artificial Insemination eng 26-30 Jun 1988 11 Dublin (Ireland)
Published 1988Texto bibliotecaFAO IT -
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18by Food and Agriculture Organization of the United Nations 12636, International Congress on Animal Reproduction. 4 (5-9 june 1961 : The Hague. NL) 16941
Published [196Texto bibliotecaUBA -
19by FAO, Rome (Italy) eng, FAO/SIDA Regional Follow-up Seminar on Animal Reproduction eng 5 Sep 1982 Lima (Peru)
Published 1983Texto bibliotecaFAO IT -
20by FAO, Rome (Italy) eng, FAO/Swedish International Veterinary Postgraduate Course on Animal Reproduction eng 1 Mar 1975 11 Stockholm (Sweden)
Published 1975Texto bibliotecaFAO IT