This is a good article. Click here for more information.
Page semi-protected
Source: Wikipedia, the free encyclopedia.

Temporal range: Cryogenian – present, 665–0 Ma
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Amorphea
Clade: Obazoa
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Clade: Choanozoa
Kingdom: Animalia
Linnaeus, 1758
  • Metazoa Haeckel 1874[1]
  • Choanoblastaea Nielsen 2008[2]
  • Gastrobionta Rothm. 1948[3]
  • Zooaea Barkley 1939[3]
  • Euanimalia Barkley 1939[3]

Animals are

embryonic development. Animals form a clade
, meaning that they arose from a single common ancestor.

Over 1.5 million

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 behaviors is known as ethology

Most living animal species belong to the infrakingdom

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

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

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.



The word animal comes from the Latin noun animal of the same meaning, which is itself derived from Latin animalis 'having breath or soul'.[6] The biological definition includes all members of the kingdom Animalia.[7] In colloquial usage, the term animal is often used to refer only to nonhuman animals.[8][9][10][11] The term metazoa is derived from Ancient Greek μετα (meta) 'after' (in biology, the prefix meta- stands for 'later') and ζῷᾰ (zōia) 'animals', plural of ζῷον zōion 'animal'.[12][13]



Animals have several characteristics that set them apart from other living things. Animals are

embryonic development that is unique to animals, allowing cells to be differentiated into specialised tissues and organs.[22]


All animals are composed of cells, surrounded by a characteristic

spicules.[24] In contrast, the cells of other multicellular organisms (primarily algae, plants, and fungi) are held in place by cell walls, and so develop by progressive growth.[25] Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, and desmosomes.[26]

With few exceptions—in particular, the sponges and

nerve tissues, which transmit signals and coordinate the body. Typically, there is also an internal digestive chamber with either one opening (in Ctenophora, Cnidaria, and flatworms) or two openings (in most bilaterians).[28]

Reproduction and development

Sexual reproduction is nearly universal in animals, such as these dragonflies.

Nearly all animals make use of some form of sexual reproduction.

gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm.[34] In most cases, a third germ layer, the mesoderm, also develops between them.[35] These germ layers then differentiate to form tissues and organs.[36]

Repeated instances of mating with a close relative during sexual reproduction generally leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits.[37][38] Animals have evolved numerous mechanisms for avoiding close inbreeding.[39]

Some animals are capable of asexual reproduction, which often results in a genetic clone of the parent. This may take place through fragmentation; budding, such as in Hydra and other cnidarians; or parthenogenesis, where fertile eggs are produced without mating, such as in aphids.[40][41]


Predators, such as this ultramarine flycatcher
(Ficedula superciliaris), feed on other animals.

Animals are categorised into ecological groups depending on their

Hydrothermal vent mussels and shrimps

Most animals rely on

Animals evolved in the sea. Lineages of arthropods colonised land around the same time as

Late Cambrian or Early Ordovician.[55] Vertebrates such as the lobe-finned fish Tiktaalik started to move on to land in the late Devonian, about 375 million years ago.[56][57] Animals occupy virtually all of earth's habitats and microhabitats, with faunas adapted to salt water, hydrothermal vents, fresh water, hot springs, swamps, forests, pastures, deserts, air, and the interiors of other organisms.[58] Animals are however not particularly heat tolerant; very few of them can survive at constant temperatures above 50 °C (122 °F)[59] or in the most extreme cold deserts of continental Antarctica.[60]



The blue whale is the largest animal that has ever lived.


titanosaur sauropod dinosaurs such as Argentinosaurus, which may have weighed as much as 73 tonnes, and Supersaurus which may have reached 39 meters.[64][65] Several animals are microscopic; some Myxozoa (obligate parasites within the Cnidaria) never grow larger than 20 μm,[66] and one of the smallest species (Myxobolus shekel) is no more than 8.5 μm when fully grown.[67]

Numbers and habitats of major phyla

The following table lists estimated numbers of described extant species for the major animal phyla,[68] along with their principal habitats (terrestrial, fresh water,[69] and marine),[70] and free-living or parasitic ways of life.[71] Species estimates shown here are based on numbers described scientifically; much larger estimates have been calculated based on various means of prediction, and these can vary wildly. For instance, around 25,000–27,000 species of nematodes have been described, while published estimates of the total number of nematode species include 10,000–20,000; 500,000; 10 million; and 100 million.[72] Using patterns within the taxonomic hierarchy, the total number of animal species—including those not yet described—was calculated to be about 7.77 million in 2011.[73][74][b]

Phylum Example Described species Land
Freshwater Free-living
wasp 1,257,000[68] Yes 1,000,000
Yes >40,000
Yes 94,000[69] Yes[70] Yes >45,000[c][71]
Mollusca snail 85,000[68]
Yes 35,000[78] Yes 60,000[78] Yes 5,000[69]
Yes[70] Yes >5,600[71]
green spotted frog facing right >70,000[68][79] Yes 23,000[80] Yes 13,000[80] Yes 18,000[69]
Yes Yes 40
29,500[68] Yes[82] Yes[70] Yes 1,300[69] Yes[70]


Yes >40,000[71]


25,000[68] Yes (soil)[70] Yes 4,000[72] Yes 2,000[69] Yes
Yes 14,000[72]
17,000[68] Yes (soil)[70] Yes[70] Yes 1,750[69] Yes Yes 400[71]
Cnidaria Table coral 16,000[68] Yes[70] Yes (few)[70] Yes[70] Yes >1,350
10,800[68] Yes[70] 200–300[69] Yes Yes[84]
7,500[68] Yes 7,500[68] Yes[70]
Bryozoa 6,000[68] Yes[70] Yes 60–80[69] Yes
2,000[68] Yes >400[85] Yes 2,000[69] Yes
Nemertea 1,350[86][87] Yes Yes Yes
1,335[68] Yes[88]
(moist plants)
Yes Yes Yes
Total number of described extant species as of 2013: 1,525,728[68]

Evolutionary origin

Evidence of animals is found as long ago as the Cryogenian period. 24-Isopropylcholestane (24-ipc) has been found in rocks from roughly 650 million years ago; it is only produced by sponges and pelagophyte algae. Its likely origin is from sponges based on molecular clock estimates for the origin of 24-ipc production in both groups. Analyses of pelagophyte algae consistently recover a Phanerozoic origin, while analyses of sponges recover a Neoproterozoic origin, consistent with the appearance of 24-ipc in the fossil record.[89][90]

The first body fossils of animals appear in the Ediacaran, represented by forms such as Charnia and Spriggina. It had long been doubted whether these fossils truly represented animals,[91][92][93] but the discovery of the animal lipid cholesterol in fossils of Dickinsonia establishes their nature.[94] Animals are thought to have originated under low-oxygen conditions, suggesting that they were capable of living entirely by anaerobic respiration, but as they became specialized for aerobic metabolism they became fully dependent on oxygen in their environments.[95]

Many animal phyla first appear in the

nematocysts as modern cnidarians do.[101]

Some palaeontologists have suggested that animals appeared much earlier than the Cambrian explosion, possibly as early as 1 billion years ago.

triploblastic worm-like animals, roughly as large (about 5 mm wide) and complex as earthworms.[104] However, similar tracks are produced by the giant single-celled protist Gromia sphaerica, so the Tonian trace fossils may not indicate early animal evolution.[105][106] Around the same time, the layered mats of microorganisms called stromatolites decreased in diversity, perhaps due to grazing by newly evolved animals.[107] Objects such as sediment-filled tubes that resemble trace fossils of the burrows of wormlike animals have been found in 1.2 gya rocks in North America, in 1.5 gya rocks in Australia and North America, and in 1.7 gya rocks in Australia. Their interpretation as having an animal origin is disputed, as they might be water-escape or other structures.[108][109]


External phylogeny

Animals are monophyletic, meaning they are derived from a common ancestor. Animals are the sister group to the choanoflagellates, with which they form the Choanozoa.[110] The dates on the phylogenetic tree indicate approximately how many millions of years ago (mya) the lineages split.[111][112][113][114][115]

Ros-Rocher and colleagues (2021) trace the origins of animals to unicellular ancestors, providing the external phylogeny shown in the cladogram. Uncertainty of relationships is indicated with dashed lines.[116]


Holomycota (inc. fungi)

1100 mya
1300 mya

Internal phylogeny

The most

Porifera, Ctenophora, Cnidaria, and Placozoa, have body plans that lack bilateral symmetry. Their relationships are still disputed; the sister group to all other animals could be the Porifera or the Ctenophora,[117] both of which lack hox genes, which are important for body plan development.[118]

Hox genes are found in the Placozoa,

Giribet and Edgecombe (2020) provide what they consider to be a consensus internal phylogeny of the animals, embodying uncertainty about the structure at the base of the tree (dashed lines).[126]












hox genes

An alternative phylogeny, from Kapli and colleagues (2021), proposes a clade Xenambulacraria for the Xenacoelamorpha + Ambulacraria; this is either within Deuterostomia, as sister to Chordata, or the Deuterostomia are recovered as paraphyletic, and Xenambulacraria is sister to the proposed clade Centroneuralia, consisting of Chordata + Protostomia.[127]


Non-bilaterians include sponges (centre) and corals (background).

Several animal phyla lack bilateral symmetry. These are the

Porifera (sea sponges), Placozoa, Cnidaria (which includes jellyfish, sea anemones, and corals), and Ctenophora
(comb jellies).

Sponges are physically very distinct from other animals, and were long thought to have diverged first, representing the oldest animal phylum and forming a

sister clade to all other animals.[128] Despite their morphological dissimilarity with all other animals, genetic evidence suggests sponges may be more closely related to other animals than the comb jellies are.[129][130] Sponges lack the complex organization found in most other animal phyla;[131] their cells are differentiated, but in most cases not organised into distinct tissues, unlike all other animals.[132] They typically feed by drawing in water through pores, filtering out small particles of food.[133]

The comb jellies and Cnidaria are radially symmetric and have digestive chambers with a single opening, which serves as both mouth and anus.

diploblastic, having only two main germ layers, ectoderm and endoderm.[136]

The tiny placozoans have no permanent digestive chamber and no symmetry; they superficially resemble amoebae.[137][138] Their phylogeny is poorly defined, and under active research.[129][139]


basis of the head. Opposed circular and longitudinal muscles enable peristaltic motion

The remaining animals, the great majority—comprising some 29 phyla and over a million species—form a clade, the Bilateria, which have a bilaterally symmetric body plan. The Bilateria are triploblastic, with three well-developed germ layers, and their tissues form distinct organs. The digestive chamber has two openings, a mouth and an anus, and there is an internal body cavity, a coelom or pseudocoelom. These animals have a head end (anterior) and a tail end (posterior), a back (dorsal) surface and a belly (ventral) surface, and a left and a right side.[140][141]

Having a front end means that this part of the body encounters stimuli, such as food, favouring

parasitic worms have extremely simplified body structures.[140][141]

Genetic studies have considerably changed zoologists' understanding of the relationships within the Bilateria. Most appear to belong to two major lineages, the

deuterostomes.[143] It is often suggested that the basalmost bilaterians are the Xenacoelomorpha, with all other bilaterians belonging to the subclade Nephrozoa[144][145][146] However, this suggestion has been contested, with other studies finding that xenacoelomorphs are more closely related to Ambulacraria than to other bilaterians.[127]

Protostomes and deuterostomes

The bilaterian gut develops in two ways. In many protostomes, the blastopore develops into the mouth, while in deuterostomes it becomes the anus.

Protostomes and deuterostomes differ in several ways. Early in development, deuterostome embryos undergo radial cleavage during cell division, while many protostomes (the Spiralia) undergo spiral cleavage.[147] Animals from both groups possess a complete digestive tract, but in protostomes the first opening of the embryonic gut develops into the mouth, and the anus forms secondarily. In deuterostomes, the anus forms first while the mouth develops secondarily.[148][149] Most protostomes have schizocoelous development, where cells simply fill in the interior of the gastrula to form the mesoderm. In deuterostomes, the mesoderm forms by enterocoelic pouching, through invagination of the endoderm.[150]

The main deuterostome phyla are the Echinodermata and the Chordata.

Hemichordata (acorn worms).[155][156]

arthropods, its body is divided into segments

The Ecdysozoa are protostomes, named after their shared

Tardigrada, are close relatives of the arthropods and share these traits. The ecdysozoans also include the Nematoda or roundworms, perhaps the second largest animal phylum. Roundworms are typically microscopic, and occur in nearly every environment where there is water;[158] some are important parasites.[159] Smaller phyla related to them are the Nematomorpha or horsehair worms, and the Kinorhyncha, Priapulida, and Loricifera. These groups have a reduced coelom, called a pseudocoelom.[160]

Spiral cleavage
in a sea snail embryo

The Spiralia are a large group of protostomes that develop by spiral cleavage in the early embryo.

Rouphozoa which includes the gastrotrichs and the flatworms. All of these are grouped as the Platytrochozoa, which has a sister group, the Gnathifera, which includes the rotifers.[162][163]

The Lophotrochozoa includes the

lugworms, and leeches. These two groups have long been considered close relatives because they share trochophore larvae.[166][167]

History of classification

invertebrates, breaking up Linnaeus's "Vermes" into 9 phyla by 1809.[168]

In the

arranged on a scale from man (with blood, 2 legs, rational soul) down through the live-bearing tetrapods (with blood, 4 legs, sensitive soul) and other groups such as crustaceans (no blood, many legs, sensitive soul) down to spontaneously generating creatures like sponges (no blood, no legs, vegetable soul). Aristotle was uncertain whether sponges were animals, which in his system ought to have sensation, appetite, and locomotion, or plants, which did not: he knew that sponges could sense touch, and would contract if about to be pulled off their rocks, but that they were rooted like plants and never moved about.[169]

In 1758,

cirripedes, annelids, crustaceans, arachnids, insects, worms, radiates, polyps, and infusorians.[168]

In his 1817

zoophytes (radiata) (echinoderms, cnidaria and other forms).[172] This division into four was followed by the embryologist Karl Ernst von Baer in 1828, the zoologist Louis Agassiz in 1857, and the comparative anatomist Richard Owen in 1860.[173]

In 1874,

Protista, leaving only the Metazoa as a synonym of Animalia.[175]

In human culture

Practical uses

Sides of beef in a slaughterhouse

The human population exploits a large number of other animal species for food, both of

domesticated livestock species in animal husbandry and, mainly at sea, by hunting wild species.[176][177] Marine fish of many species are caught commercially for food. A smaller number of species are farmed commercially.[176][178][179] Humans and their livestock make up more than 90% of the biomass of all terrestrial vertebrates, and almost as much as all insects combined.[180]

Working animals including cattle and horses have been used for work and transport from the first days of agriculture.[191]

Animals such as the fruit fly Drosophila melanogaster serve a major role in science as experimental models.[192][193][194][195] Animals have been used to create vaccines since their discovery in the 18th century.[196] Some medicines such as the cancer drug trabectedin are based on toxins or other molecules of animal origin.[197]

A gun dog retrieving a duck during a hunt

People have used

blowpipe darts.[201][202]
A wide variety of animals are kept as pets, from invertebrates such as tarantulas, octopuses, and
praying mantises,[203] reptiles such as snakes and chameleons,[204] and birds including canaries, parakeets, and parrots[205] all finding a place. However, the most kept pet species are mammals, namely dogs, cats, and rabbits.[206][207][208] There is a tension between the role of animals as companions to humans, and their existence as individuals with rights of their own.[209]
A wide variety of terrestrial and aquatic animals are hunted for sport.[210]

Symbolic uses

Still Life with Lobster and Oysters by Alexander Coosemans
, c. 1660

Animals have been the

Animals including

signs of the Western and Chinese zodiacs are also based on animals.[227][228]

See also


  1. ^ Henneguya zschokkei does not have mitochondrial DNA or utilize aerobic respiration.[19]
  2. ^ The application of DNA barcoding to taxonomy further complicates this; a 2016 barcoding analysis estimated a total count of nearly 100,000 insect species for Canada alone, and extrapolated that the global insect fauna must be in excess of 10 million species, of which nearly 2 million are in a single fly family known as gall midges (Cecidomyiidae).[75]
  3. ^ Not including parasitoids.[71]
  4. ^ Compare File:Annelid redone w white background.svg for a more specific and detailed model of a particular phylum with this general body plan.
  5. ^ In his History of Animals and Parts of Animals.
  6. ^ The French prefix une espèce de is pejorative.[171]


  1. S2CID 242704712
  2. .
  3. ^ .
  4. ^ "animalia". Dictionary. Retrieved 12 May 2024.
  5. S2CID 22630754
  6. . 'having the breath of life', from anima 'air, breath, life'.
  7. Houghton Mifflin
    . 2006.
  8. ^ "animal". English Oxford Living Dictionaries. Archived from the original on 26 July 2018. Retrieved 26 July 2018.
  9. PMID 24198791
  10. ^ "The use of non-human animals in research". Royal Society. Archived from the original on 12 June 2018. Retrieved 7 June 2018.
  11. ^ "Nonhuman definition and meaning". Collins English Dictionary. Archived from the original on 12 June 2018. Retrieved 7 June 2018.
  12. ^ "Metazoan". Merriam-Webster. Archived from the original on 6 July 2022. Retrieved 6 July 2022.
  13. ^ "Metazoa". Collins. Archived from the original on 30 July 2022. Retrieved 6 July 2022. and further meta- (sense 1) Archived 30 July 2022 at the Wayback Machine and -zoa Archived 30 July 2022 at the Wayback Machine.
  14. .
  15. ^ Davidson, Michael W. "Animal Cell Structure". Archived from the original on 20 September 2007. Retrieved 20 September 2007.
  16. ^ "Palaeos:Metazoa". Palaeos. Archived from the original on 28 February 2018. Retrieved 25 February 2018.
  17. ^ Bergman, Jennifer. "Heterotrophs". Archived from the original on 29 August 2007. Retrieved 30 September 2007.
  18. PMID 12594915
  19. ^ Andrew, Scottie (26 February 2020). "Scientists discovered the first animal that doesn't need oxygen to live. It's changing the definition of what an animal can be". CNN. Archived from the original on 10 January 2022. Retrieved 28 February 2020.
  20. PMID 20370917
  21. ^ Saupe, S. G. "Concepts of Biology". Archived from the original on 21 November 2007. Retrieved 30 September 2007.
  22. .
  23. from the original on 23 December 2016. Retrieved 29 August 2017.
  24. .
  25. .
  26. .
  27. . Retrieved 19 May 2020.
  28. . Retrieved 8 January 2016.
  29. .
  30. .
  31. .
  32. .
  33. ^ Hamilton, William James; Boyd, James Dixon; Mossman, Harland Winfield (1945). Human embryology: (prenatal development of form and function). Williams & Wilkins. p. 330.
  34. .
  35. ^ The Encyclopedia Americana: a library of universal knowledge, Volume 10. Encyclopedia Americana Corp. 1918. p. 281.
  36. .
  37. .
  38. .
  39. .
  40. .
  41. ^ Schatz, Phil. "Concepts of Biology: How Animals Reproduce". OpenStax College. Archived from the original on 6 March 2018. Retrieved 5 March 2018.
  42. .
  43. .
  44. .
  45. .
  46. ^ Caro, Tim (2005). Antipredator Defenses in Birds and Mammals. University of Chicago Press. pp. 1–6 and passim.
  47. S2CID 207051421
  48. ^ Stevens, Alison N. P. (2010). "Predation, Herbivory, and Parasitism". Nature Education Knowledge. 3 (10): 36. Archived from the original on 30 September 2017. Retrieved 12 February 2018.
  49. S2CID 84430254
  50. .
  51. .
  52. .
  53. .
  54. .
  55. .
  56. .
  57. .
  58. .
  59. (PDF) from the original on 24 April 2019.
  60. ^ "Land animals". British Antarctic Survey. Archived from the original on 6 November 2018. Retrieved 7 March 2018.
  61. ^ .
  62. ^ Davies, Ella (20 April 2016). "The longest animal alive may be one you never thought of". BBC Earth. Archived from the original on 19 March 2018. Retrieved 1 March 2018.
  63. ^ "Largest mammal". Guinness World Records. Archived from the original on 31 January 2018. Retrieved 1 March 2018.
  64. S2CID 56028251
  65. ^ Curtice, Brian (2020). "Society of Vertebrate Paleontology" (PDF). Archived (PDF) from the original on 19 October 2021. Retrieved 30 December 2022.
  66. ^ Fiala, Ivan (10 July 2008). "Myxozoa". Tree of Life Web Project. Archived from the original on 1 March 2018. Retrieved 4 March 2018.
  67. PMID 23024499
  68. ^ from the original on 24 April 2019. Retrieved 2 March 2018.
  69. ^ .
  70. ^ a b c d e f g h i j k l m n Hogenboom, Melissa. "There are only 35 kinds of animal and most are really weird". BBC Earth. Archived from the original on 10 August 2018. Retrieved 2 March 2018.
  71. ^ .
  72. ^ .
  73. ^ "How many species on Earth? About 8.7 million, new estimate says". 24 August 2011. Archived from the original on 1 July 2018. Retrieved 2 March 2018.
  74. PMID 21886479
  75. .
  76. . Stork notes that 1m insects have been named, making much larger predicted estimates.
  77. .
  78. ^ .
  79. ^ Uetz, P. "A Quarter Century of Reptile and Amphibian Databases". Herpetological Review. 52: 246–255. Archived from the original on 21 February 2022. Retrieved 2 October 2021 – via ResearchGate.
  80. ^ .
  81. ISBN 978-0-19-878555-2. Trichomycteridae ... includes obligate parasitic fish. Thus 17 genera from 2 subfamilies, Vandelliinae; 4 genera, 9spp. and Stegophilinae
    ; 13 genera, 31 spp. are parasites on gills (Vandelliinae) or skin (stegophilines) of fish.
  82. .
  83. ^ . Retrieved 19 May 2020.
  84. . Retrieved 2 March 2018.
  85. ^ Fontaneto, Diego. "Marine Rotifers | An Unexplored World of Richness" (PDF). JMBA Global Marine Environment. pp. 4–5. Archived (PDF) from the original on 2 March 2018. Retrieved 2 March 2018.
  86. S2CID 239872311
    . Retrieved 18 January 2023.
  87. . Retrieved 18 January 2023.
  88. .
  89. .
  90. .
  91. .
  92. .
  93. .
  94. ^ .
  95. .
  96. ^ "Stratigraphic Chart 2022" (PDF). International Stratigraphic Commission. February 2022. Archived (PDF) from the original on 2 April 2022. Retrieved 25 April 2022.
  97. S2CID 6694681
  98. ^ "New Timeline for Appearances of Skeletal Animals in Fossil Record Developed by UCSB Researchers". The Regents of the University of California. 10 November 2010. Archived from the original on 3 September 2014. Retrieved 1 September 2014.
  99. from the original on 16 July 2018. Retrieved 28 February 2018.
  100. ^ "The Tree of Life". The Burgess Shale. Royal Ontario Museum. 10 June 2011. Archived from the original on 16 February 2018. Retrieved 28 February 2018.
  101. ^
    PMID 35879540
  102. .
  103. .
  104. .
  105. .
  106. ^ Reilly, Michael (20 November 2008). "Single-celled giant upends early evolution". NBC News. Archived from the original on 29 March 2013. Retrieved 5 December 2008.
  107. The Paleontological Society. pp. 289–317. Archived
    (PDF) from the original on 30 October 2019. Retrieved 3 March 2018.
  108. .
  109. .
  110. .
  111. .
  112. .
  113. ^ "Raising the Standard in Fossil Calibration". Fossil Calibration Database. Archived from the original on 7 March 2018. Retrieved 3 March 2018.
  114. PMID 30373720
  115. .
  116. .
  117. .
  118. .
  119. ^ "Evolution and Development" (PDF). Carnegie Institution for Science Department of Embryology. 1 May 2012. p. 38. Archived from the original (PDF) on 2 March 2014. Retrieved 4 March 2018.
  120. S2CID 41288638
  121. .
  122. .
  123. (PDF) from the original on 26 February 2018.
  124. ^ Zimmer, Carl (4 May 2018). "The Very First Animal Appeared Amid an Explosion of DNA". The New York Times. Archived from the original on 4 May 2018. Retrieved 4 May 2018.
  125. PMID 29712911
  126. . Retrieved 27 May 2023.
  127. ^ .
  128. .
  129. ^ .
  130. .
  131. .
  132. Prentice-Hall
    . p. 428.
  133. .
  134. .
  135. .
  136. .
  137. .
  138. ^ "Introduction to Placozoa". UCMP Berkeley. Archived from the original on 25 March 2018. Retrieved 10 March 2018.
  139. S2CID 4415492
  140. ^ .
  141. ^ (PDF) from the original on 24 April 2019. Retrieved 4 March 2018.
  142. from the original on 17 June 2020. Retrieved 4 March 2018.
  143. .
  144. .
  145. (PDF) from the original on 24 April 2019. Retrieved 4 March 2018.
  146. from the original on 30 July 2022. Retrieved 21 February 2022.
  147. .
  148. .
  149. from the original on 28 October 2018. Retrieved 1 March 2018.
  150. .
  151. .
  152. .
  153. .
  154. .
  155. .
  156. .
  157. .
  158. .
  159. .
  160. .
  161. .
  162. ^ .
  163. .
  164. .
  165. ^ Speer, Brian R. (2000). "Introduction to the Lophotrochozoa | Of molluscs, worms, and lophophores..." UCMP Berkeley. Archived from the original on 16 August 2000. Retrieved 28 February 2018.
  166. PMID 12116426
  167. .
  168. ^ .
  169. .
  170. ^ Linnaeus, Carl (1758). Systema naturae per regna tria naturae :secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis (in Latin) (10th ed.). Holmiae (Laurentii Salvii). Archived from the original on 10 October 2008. Retrieved 22 September 2008.
  171. ^ "Espèce de". Reverso Dictionnnaire. Archived from the original on 28 July 2013. Retrieved 1 March 2018.
  172. .
  173. ^ .
  174. ^ Haeckel, Ernst (1874). Anthropogenie oder Entwickelungsgeschichte des menschen (in German). W. Engelmann. p. 202.
  175. .
  176. ^ a b "Fisheries and Aquaculture". Food and Agriculture Organization. Archived from the original on 19 May 2009. Retrieved 8 July 2016.
  177. ^ a b "Graphic detail Charts, maps and infographics. Counting chickens". The Economist. 27 July 2011. Archived from the original on 15 July 2016. Retrieved 23 June 2016.
  178. .
  179. ^ "World Review of Fisheries and Aquaculture" (PDF). FAO. Archived (PDF) from the original on 28 August 2015. Retrieved 13 August 2015.
  180. ISSN 1543-5938
  181. ^ "Shellfish climbs up the popularity ladder". Seafood Business. January 2002. Archived from the original on 5 November 2012. Retrieved 8 July 2016.
  182. ^ "Breeds of Cattle at Cattle Today". Archived from the original on 15 July 2011. Retrieved 15 October 2013.
  183. ^ Lukefahr, S. D.; Cheeke, P. R. "Rabbit project development strategies in subsistence farming systems". Food and Agriculture Organization. Archived from the original on 6 May 2016. Retrieved 23 June 2016.
  184. ^ "Ancient fabrics, high-tech geotextiles". Natural Fibres. Archived from the original on 20 July 2016. Retrieved 8 July 2016.
  185. ^ "Cochineal and Carmine". Major colourants and dyestuffs, mainly produced in horticultural systems. FAO. Archived from the original on 6 March 2018. Retrieved 16 June 2015.
  186. ^ "Guidance for Industry: Cochineal Extract and Carmine". FDA. Archived from the original on 13 July 2016. Retrieved 6 July 2016.
  187. ^ "How Shellac Is Manufactured". The Mail (Adelaide, SA : 1912–1954). 18 December 1937. Archived from the original on 30 July 2022. Retrieved 17 July 2015.
  188. S2CID 13150932
  189. .
  190. .
  191. . Retrieved 22 February 2018.
  192. ^ "Genetics Research". Animal Health Trust. Archived from the original on 12 December 2017. Retrieved 24 June 2016.
  193. ^ "Drug Development". Animal Archived from the original on 8 June 2016. Retrieved 24 June 2016.
  194. ^ "Animal Experimentation". BBC. Archived from the original on 1 July 2016. Retrieved 8 July 2016.
  195. ^ "EU statistics show decline in animal research numbers". Speaking of Research. 2013. Archived from the original on 6 October 2017. Retrieved 24 January 2016.
  196. ^ "Vaccines and animal cell technology". Animal Cell Technology Industrial Platform. 10 June 2013. Archived from the original on 13 July 2016. Retrieved 9 July 2016.
  197. ^ "Medicines by Design". National Institute of Health. Archived from the original on 4 June 2016. Retrieved 9 July 2016.
  198. .
  199. ^ "History of Falconry". The Falconry Centre. Archived from the original on 29 May 2016. Retrieved 22 April 2016.
  200. .
  201. ^ "AmphibiaWeb – Dendrobatidae". AmphibiaWeb. Archived from the original on 10 August 2011. Retrieved 10 October 2008.
  202. ^ Heying, H. (2003). "Dendrobatidae". Animal Diversity Web. Archived from the original on 12 February 2011. Retrieved 9 July 2016.
  203. ^ "Other bugs". Keeping Insects. 18 February 2011. Archived from the original on 7 July 2016. Retrieved 8 July 2016.
  204. ^ Kaplan, Melissa. "So, you think you want a reptile?". Archived from the original on 3 July 2016. Retrieved 8 July 2016.
  205. ^ "Pet Birds". PDSA. Archived from the original on 7 July 2016. Retrieved 8 July 2016.
  206. ^ "Animals in Healthcare Facilities" (PDF). 2012. Archived from the original (PDF) on 4 March 2016.
  207. ^ The Humane Society of the United States. "U.S. Pet Ownership Statistics". Archived from the original on 7 April 2012. Retrieved 27 April 2012.
  208. ^ "U.S. Rabbit Industry profile" (PDF). United States Department of Agriculture. Archived from the original (PDF) on 20 October 2013. Retrieved 10 July 2013.
  209. .
  210. .
  211. ^ Jones, Jonathan (27 June 2014). "The top 10 animal portraits in art". The Guardian. Archived from the original on 18 May 2016. Retrieved 24 June 2016.
  212. from the original on 14 June 2016. Retrieved 24 June 2016.
  213. .
  214. .
  215. .
  216. ^ .
  217. ^ a b "Deer". Trees for Life. Archived from the original on 14 June 2016. Retrieved 23 June 2016.
  218. ^ Louis, Chevalier de Jaucourt (Biography) (January 2011). "Butterfly". Encyclopedia of Diderot and d'Alembert. Archived from the original on 11 August 2016. Retrieved 10 July 2016.
  219. ^ Hutchins, M., Arthur V. Evans, Rosser W. Garrison and Neil Schlager (Eds) (2003) Grzimek's Animal Life Encyclopedia, 2nd edition. Volume 3, Insects. Gale, 2003.
  220. .
  221. ^ Biswas, Soutik (15 October 2015). "Why the humble cow is India's most polarising animal". BBC. Archived from the original on 22 November 2016. Retrieved 9 July 2016.
  222. ^ van Gulik, Robert Hans. Hayagrīva: The Mantrayānic Aspect of Horse-cult in China and Japan. Brill Archive. p. 9.
  223. ^ Grainger, Richard (24 June 2012). "Lion Depiction across Ancient and Modern Religions". Alert. Archived from the original on 23 September 2016. Retrieved 6 July 2016.
  224. ^ Read, Kay Almere; Gonzalez, Jason J. (2000). Mesoamerican Mythology. Oxford University Press. pp. 132–134.
  225. S2CID 53595088
  226. ^ McCone, Kim R. (1987). "Hund, Wolf, und Krieger bei den Indogermanen". In Meid, W. (ed.). Studien zum indogermanischen Wortschatz. Innsbruck. pp. 101–154.{{cite book}}: CS1 maint: location missing publisher (link)
  227. ^ Lau, Theodora (2005). The Handbook of Chinese Horoscopes. Souvenir Press. pp. 2–8, 30–35, 60–64, 88–94, 118–124, 148–153, 178–184, 208–213, 238–244, 270–278, 306–312, 338–344.
  228. .

External links

This page is based on the copyrighted Wikipedia article: Animal. Articles is available under the CC BY-SA 3.0 license; additional terms may apply.Privacy Policy