Animals you won't make as pet even if you were given an offer.

Animals (also called Metazoa ) are multicellular

eukaryotic organisms that form the biological kingdom Animalia . With few exceptions, animals

consume organic material , breathe oxygen , are

able to move, can reproduce sexually , and grow from a hollow sphere of cells, the blastula , during embryonic development . Over 1.5 million

living animal species have been described—of which around 1 million are insects —but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 micrometres (0.00033 in) to 33.6 metres (110 ft). They have complex interactions with each other and their environments, forming intricate food webs . The kingdom Animalia includes humans but in colloquial use the term

animal often refers only to non-human animals. The scientific study of animals is known as

zoology.

Most living animal species are in Bilateria, a

clade whose members have a bilaterally symmetric body plan. The Bilateria include the

protostomes —in which many groups of

invertebrates are found, such as nematodes,

arthropods, and molluscs —and the

deuterostomes , containing both the

echinoderms as well as the chordates , the latter containing the vertebrates . Life forms interpreted as early animals were present in the

Ediacaran biota of the late Precambrian . Many modern animal phyla became clearly established in the fossil record as marine species during the

Cambrian explosion , which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified; these may have arisen from a single

common ancestor that lived 650 million years ago .

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 ( synonymous for 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 animal taxa.

Humans make use of many other animal species , such as for food (including meat , milk, and eggs ), for materials (such as leather and

wool ), and also as pets , and for transports, as

working animals. Dogs have been used in hunting , while many terrestrial and aquatic animals were hunted for sports. Non-human animals have appeared in art from the earliest times and are featured in mythology and religion.

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