Temporal range: Cryogenian – Present, 670 –0Ma
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Scientific classification e
List of animal phyla
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals can move, consume organic material, breathe oxygen, reproduce sexually, and develop from an embryonic stage made of a hollow ball of cells, the blastula. There are over 1.5 million living animal species, of which around 1 million …show more content…
In 1758, Carl Linnaeus created the first hierarchical classification, dividing the animals into Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. This system was broken up by Jean-Baptiste de Lamarck, who by 1809 had identified 14 animal phyla. In 1817 Georges Cuvier created four major branches with different body plans, namely vertebrates, molluscs, articulated animals, and zoophytes. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the single-celled Protozoa (no longer considered to be animals). Today the classification of animals relies on advanced techniques such as molecular phylogenetics, which continue to unveil the evolutionary relationships between animal groups.
Humans make use of many other animal species for food including meat, milk, and eggs, for materials such as leather and wool, as pets, and as working animals for power and transport. Dogs especially have been used in hunting, while many terrestrial and aquatic animals are hunted for sport. Animals have appeared in art from the earliest times, and feature also in mythology and …show more content…
Animals are eukaryotic and multicellular, which separates them from prokaryotic bacteria and eukaryotic but unicellular protists. Unlike plants and algae, which produce their own nutrients (and, with fungi, have rigid cell walls), animals are heterotrophic, consuming organic material and digesting it internally. With very few exceptions, animals breathe oxygen and respire aerobically. All animals are motile (able to spontaneously move their bodies) during at least part of their life cycle, but some animals, such as sponges, corals, mussels, and barnacles, later become sessile. The blastula is a stage in embryonic development that is unique to most animals, allowing cells to be differentiated into specialized tissues and