animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in which their body consists of 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 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, containing animals such as nematodes, arthropods, flatworms, annelids and molluscs, and the deuterostomes, containing the echinoderms and the chordates, the latter including 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 539 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 (now 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 taxa.
Humans make use of many animal species, such as for food (including meat, milk, and eggs), for materials (such as leather and wool), as pets, and as working animals including for transport. Dogs have been used in hunting, as have birds of prey, while many terrestrial and aquatic animals were hunted for sports. Nonhuman animals have appeared in art from the earliest times and are featured in mythology and religion.
animal
a living organism characterized by voluntary movement
animal(a)
marked by the appetites and passions of the body; "animal instincts"; "carnal knowledge"; "fleshly desire"; "a sensual delight in eating"; "music is the only sensual pleasure without vice"
animal
noun: Any of numerous multicellular eukaryotic organisms of the kingdom Metazoa (or Animalia) that ingest food rather than manufacturing it themselves and are usually able to move about during at least part of their life cycle. Sponges, jellyfishes, flatworms, mollusks, arthropods, and vertebrates are animals.
noun: An animal organism other than a human, especially a mammal.
noun: A person who behaves in a bestial or brutish manner.
noun: A human considered with respect to his or her physical nature, as opposed to rational or spiritual nature.
noun: A person having a specified aptitude or set of interests.
adjective: Relating to, characteristic of, or derived from an animal or animals, especially when not human.
adjective: Relating to the physical as distinct from the rational or spiritual nature of people.
undefined: Pertaining to sensation. See
undefined: Having life; living; animate.
undefined: Pertaining to the merely sentient part of a living being, as distinguished from the intellectual, rational, or spiritual part; of man, pertaining to those parts of his nature which he shares with inferior animals.
undefined: Of, pertaining to, or derived from animals.
noun: A sentient living being; an individual, organized, animated, and sentient portion of matter; in zoology, one of the Animalia; a member of the animal kingdom, as distinguished from a vegetable or a mineral.
| cross-reference | equivalent | etymologically-related-term | has_topic | same-context | synonym |
|---|---|---|---|---|---|
| aggregate animals | physical | Animalia | Pets | advance | Adamic |
| animal anæretics | anima | being | Angora goat | ||
| animal charcoal | animate | body | Arctic fox | ||
| animal economy | animus | child | Belgian hare | ||
| animal electricity | country | Caffre cat | |||
| animal food | creature | Circean | |||
| animal force | deliberative | Draconian | |||
| animal function | evidence | Goth | |||
| animal heat | fish | Gothic | |||
| animal kingdom | horse | Indian buffalo |