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Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (/ ˌ æ n ɪ ˈ m eɪ l i ə / [4]).With few exceptions, animals consume organic material, breathe oxygen, have myocytes and 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 in total. Animals range in size from 8.5 millionths of a metre to 33.6 metres (110 ft) long and have complex interactions with each other and their environments, forming intricate food webs.
The following outline is provided as an overview of and topical guide to zoology: . Zoology – study of animals.Zoology, or "animal biology", is the branch of biology that relates to the animal kingdom, including the identification, structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems.
A mammal (from Latin mamma 'breast') [1] is a vertebrate animal of the class Mammalia (/ m ə ˈ m eɪ l i. ə /).Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle ear bones.
This is an accepted version of this page This is the latest accepted revision, reviewed on 11 January 2025. Group of animals including lepidosaurs, testudines, and archosaurs This article is about the animal class. For other uses, see Reptile (disambiguation). Reptiles Temporal range: Late Carboniferous–Present PreꞒ Ꞓ O S D C P T J K Pg N Tuatara Saltwater crocodile Common box turtle ...
There are 107 classes of animals in 33 phyla in this list. However, different sources give different numbers of classes and phyla. For example, Protura, Diplura, and Collembola are often considered to be the three orders in the class Entognatha. This list should by no means be considered complete and authoritative and should be used carefully.
Zoology (UK: / z u ˈ ɒ l ə dʒ i / zoo-OL-ə-jee, US: / z oʊ ˈ ɒ l ə dʒ i / zoh-OL-ə-jee) [1] is the scientific study of animals.Its studies include the structure, embryology, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems.
[1] [2] Historically, protozoans were regarded as "one-celled animals". When first introduced by Georg Goldfuss , in 1818, the taxon Protozoa was erected as a class within the Animalia, [ 3 ] with the word 'protozoa' meaning "first animals", because they often possess animal -like behaviours, such as motility and predation , and lack a cell ...