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Animals
Temporal range: "Cryogenian – "Present, 670 –0Ma
StarfishCnidariaBivalveTardigradeMalacostracaArachnidSpongeArthropodMammalBryozoaAcanthocephalaFlatwormCephalopodAnnelidTunicateFishBirdPhoronidaAnimal diversity.png
""About this image
"Scientific classification "e
Domain: "Eukaryota
(unranked): "Unikonta
(unranked): "Opisthokonta
(unranked): "Holozoa
(unranked): "Filozoa
Kingdom: Animalia
"Linnaeus, "1758
"Phyla
"Synonyms
  • Metazoa

Animals are "multicellular "eukaryotic organisms that form the "biological kingdom Animalia. With few exceptions, animals "consume organic material, "breathe oxygen, are "able to move, "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 animals in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres (110 ft) and have "complex interactions with each other and their environments, forming intricate "food webs. The study of animals is called "zoology.

Most living animal species are classified in the "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, to which "echinoderms and "chordates (including the "vertebrates) belong. Life forms interpreted as early animals were present in the "Ediacaran biota of the late "Precambrian. Most modern animal phyla became clearly established in the "fossil record as "marine species during the "Cambrian explosion around 542 million years ago.

"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 the late-1800s, "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 animal "taxa.

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 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 are featured in mythology and religion.

Contents

Etymology[edit]

The word "animal" comes from the Latin animalis, meaning having breath, having soul or living being.[1] The biological definition of the word refers to all members of the kingdom Animalia,[2] whereas in "colloquial use, animal often refers to non-human animals. Sometimes the word may refer to only other vertebrates, or just "mammals.[3]

Characteristics[edit]

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Animals are unique in having the ball of cells of the early "embryo (1) develop into a hollow ball or "blastula (2).

Animals have several characteristics that set them apart from other living things. Animals are "eukaryotic and multicellular,[4][5] unlike bacteria, which are "prokaryotic, and unlike "protists, which are eukaryotic but "unicellular. Unlike plants and "algae, which "produce their own nutrients[6] animals are "heterotrophic,[5][7] feeding on organic material and digesting it internally.[8] With very few exceptions, animals breathe oxygen and "respire aerobically.[9] All animals are "motile[10] (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,[11] allowing "cells to be differentiated into specialised tissues and organs.

Structure[edit]

All animals are composed of cells, surrounded by a characteristic "extracellular matrix composed of "collagen and elastic "glycoproteins.[12] During development, the animal extracellular matrix forms a relatively flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible. This may be calcified, forming structures such as "shells, "bones, and "spicules.[13] 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.[14] Animal cells uniquely possess the "cell junctions called "tight junctions, "gap junctions, and "desmosomes.[15]

With few exceptions—in particular, the sponges and "placozoans—animal bodies are differentiated into "tissues.[16] These include "muscles, which enable locomotion, and "nerve tissues, which transmit signals and coordinate the body. Typically, there is also an internal "digestive chamber with either one opening (as in flatworms) or two openings (as in deuterostomes).[17]

Reproduction and development[edit]

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

Nearly all animals make use of some form of sexual reproduction.[18] They produce "haploid "gametes by "meiosis; the smaller, motile gametes are "spermatozoa and the larger, non-motile gametes are "ova.[19] These fuse to form "zygotes,[20] which develop via "mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, and develop into a new sponge.[21] In most other groups, the blastula undergoes more complicated rearrangement.[22] It first "invaginates to form a "gastrula with a digestive chamber and two separate "germ layers, an external "ectoderm and an internal "endoderm.[23] In most cases, a third germ layer, the "mesoderm, also develops between them.[24] These germ layers then differentiate to form tissues and organs.[25]

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.[26][27] Animals have evolved numerous mechanisms for "avoiding close inbreeding.[28] In some species, such as the "splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality.[29]

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.[30][31]

Ecology[edit]

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

Animals are categorised into "ecological groups depending on how they obtain or consume organic material, including "carnivores, "herbivores, "omnivores, "detritivores,[32] and "parasites.[33] Interactions between animals form complex "food webs. In carnivorous or omnivorous species, "predation is a "consumer-resource interaction where a predator feeds on another organism (called its prey).[34] Selective pressures imposed on one another lead to an "evolutionary arms race between predator and prey, resulting in various "anti-predator adaptations.[35][36] Almost all multicellular predators are animals.[37] Some "consumers use multiple methods; for example, in "parasitoid wasps, the larvae feed on the hosts' living tissues, killing them in the process,[38] but the adults primarily consume nectar from flowers.[39] Other animals may have very specific "feeding behaviours, such as "hawksbill sea turtles that primarily "eat sponges.[40]

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"Hydrothermal vent mussels and shrimps

Most animals rely on the energy produced by plants through "photosynthesis. Herbivores eat plant material directly, while carnivores, and other animals on higher "trophic levels, typically acquire energy (in the form of "reduced carbon) by eating other animals. The "carbohydrates, "lipids, "proteins, and other biomolecules are broken down to allow the animal to grow and to sustain biological processes such as "locomotion.[41][42][43] Animals living close to "hydrothermal vents and "cold seeps on the dark "sea floor do not depend on the energy of sunlight.[44] Rather, "archaea and bacteria in these locations produce organic matter through "chemosynthesis (by oxidizing inorganic compounds, such as methane) and form the base of the local food web.[45]

Animals originally evolved in the sea. Lineages of arthropods colonised land around the same time as "land plants, probably between 510–471 million years ago during the "Late Cambrian or Early "Ordovician.[46] "Vertebrates such as the "lobe-finned fish "Tiktaalik started to move on to land in the late "Devonian, about 375 million years ago.[47][48] Animals occupy virtually all of earth's "habitats and microhabitats, including salt water, hydrothermal vents, fresh water, hot springs, swamps, forests, pastures, deserts, air, and the interiors of animals, plants, fungi and rocks.[49] Animals are however not particularly "heat tolerant; very few of them can survive at constant temperatures above 50 °C (122 °F).[50] Only very few species of animals (mostly "nematodes) inhabit the most extreme cold deserts of continental "Antarctica.[51]

Diversity[edit]

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

Largest and smallest[edit]

The "blue whale (Balaenoptera musculus) is the largest animal that has ever lived, weighing up to 190 metric "tonnes and measuring up to 33.6 metres (110 ft) long.[52][53][54] The largest extant terrestrial animal is the "African bush elephant (Loxodonta africana), weighing up to 12.25 tonnes[52] and measuring up to 10.67 metres (35.0 ft) long.[52] The largest terrestrial animals that ever lived were "titanosaur "sauropod dinosaurs such as "Argentinosaurus, which may have weighed as much as 73 tonnes.[55] Several animals are microscopic; some "Myxozoa ("obligate parasites within the Cnidaria) never grow larger than 20 "µm,[56] and one of the smallest species (Myxobolus shekel) is no more than 8.5 µm when fully grown.[57]

Numbers and habitats[edit]

The following table lists estimated numbers of described extant species for the animal groups with the largest numbers of species,[58] along with their principal habitats (terrestrial, fresh water,[59] and marine),[60] and free-living or parasitic ways of life.[61] 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.[62] 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.[63][64] [a]

"Phylum Example No. of
Species
"Land "Sea "Fresh
water
Free-
living
"Parasitic
"Annelids ""Nerr0328.jpg 17,000[58] Yes (soil)[60] Yes[60] 1,750[59] Yes 400[61]
"Arthropods ""wasp 1,257,000[58] 1,000,000
(insects)[66]
>40,000
(Malac-
ostraca)[67]
94,000[59] Yes[60] >45,000[b][61]
"Bryozoa ""Bryozoan at Ponta do Ouro, Mozambique (6654415783).jpg 6,000[58] Yes[60] 60-80[59] Yes
"Chordates ""green spotted frog facing right 65,000[58]
45,000[68]

23,000[68]

13,000[68]
18,000[59]
9,000[68]
Yes 40
(catfish)[69][61]
"Cnidaria ""Table coral 16,000[58] Yes[60] Yes (few)[60] Yes[60] >1,350
(Myxozoa)[61]
"Echinoderms ""Starfish, Caswell Bay - geograph.org.uk - 409413.jpg 7,500[58] 7,500[58] Yes[60]
"Molluscs ""snail 85,000[58]
107,000[70]

35,000[70]

60,000[70]
5,000[59]
12,000[70]
Yes[60] >5,600[61]
"Nematodes ""CelegansGoldsteinLabUNC.jpg 25,000[58] Yes (soil)[60] 4,000[62] 2,000[59] 11,000[62] 14,000[62]
"Platyhelminthes ""Pseudoceros dimidiatus.jpg 29,500[58] Yes[71] Yes[60] 1,300[59] Yes[60] >40,000[61]
"Rotifers ""20090730 020239 Rotifer.jpg 2,000[58] >400[72] 2,000[59] Yes
"Sponges ""A colourful Sponge on the Fathom.jpg 10,800[58] Yes[60] 200-300[59] Yes Yes[73]
Total number of described species as of 2013: 1,525,728[58]

Evolutionary origin[edit]

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If "Dickinsonia costata from the "Ediacaran biota, (c. 635–542 Mya), is indeed an animal, then it is one of the earliest animal species known.

The first "fossils that might represent animals appear in the 665-million-year-old rocks of the "Trezona Formation of "South Australia. These fossils are interpreted as being early sponges.[74]

The next oldest fossils that could be animals are found in the "Ediacaran biota, towards the end of the Precambrian, around 610 million years ago.[75] These are difficult to relate to later fossils. Some may represent precursors of modern phyla, but they may be separate groups, and it is possible they are not animals at all.[76]

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"Anomalocaris canadensis is one of the many animal species that emerged in the "Cambrian explosion, starting some 542 million years ago, and found in the fossil beds of the "Burgess shale.

Most known animal phyla first appear in the fossil record during the "Cambrian explosion, starting about 542 million years ago, in beds such as the "Burgess shale. Extant phyla in these rocks include "molluscs, "brachiopods, "onychophorans, "tardigrades, "arthropods, "echinoderms and "hemichordates, along with numerous now-extinct forms. The apparent suddenness of the event may however be an artefact of the fossil record, rather than showing that all these animals appeared simultaneously.[77][78][79][80]

Some palaeontologists have suggested that animals appeared much earlier than the Cambrian explosion, possibly as early as 1 billion years ago.[81] "Trace fossils such as tracks and burrows found in the "Tonian period may indicate the presence of "triploblastic worm-like animals, roughly as large (about 5 mm wide) and complex as earthworms.[82] However, similar tracks are produced today by the giant single-celled protist "Gromia sphaerica, so the Tonian trace fossils may not indicate early animal evolution.[83][84] Around the same time, another line of evidence may indicate the appearance of grazing animals: the layered mats of "microorganisms called "stromatolites decreased in diversity, perhaps due to grazing.[85]

Phylogeny[edit]

Animals are "monophyletic, meaning they are derived from a common ancestor and form a single "clade within the "Apoikozoa. The "Choanoflagellata are their sister clade.[86] The most "basal animals, the "Porifera, "Ctenophora, Cnidaria, and Placozoa, have body plans that lack "bilateral symmetry, but their relationships are still disputed. As of 2017, the Porifera are considered the basalmost animals.[87][88][89][90][91][92] An alternative to the Porifera could be the Ctenophora,[93][94][95][96] which like the Porifera lack "hox genes, "important in body plan development. These genes are found in the Placozoa[97][98] and the higher animals, the Bilateria.[99][100]

The "phylogenetic tree (of major lineages only) indicates approximately how many millions of years ago (mya) the lineages split.[101][102][103]

"Apoikozoa


"Choanoflagellata ""Desmarella moniliformis.jpg


Animalia


"Porifera ""Reef3859 - Flickr - NOAA Photo Library.jpg


"Eumetazoa


"Ctenophora ""Comb jelly.jpg


"ParaHoxozoa


"Placozoa ""Trichoplax adhaerens photograph.png


"Planulozoa


"Cnidaria ""Cauliflour Jellyfish, Cephea cephea at Marsa Shouna, Red Sea, Egypt SCUBA.jpg


"Bilateria


"Xenacoelomorpha ""Proporus sp.png


"Nephrozoa

"Deuterostomia


"Chordata and allies ""Cyprinus carpio3.jpg



"Echinodermata ""Portugal 20140812-DSC01434 (21371237591).jpg



"Protostomia

"Ecdysozoa


"Arthropoda and allies ""Long nosed weevil edit.jpg



"Nematoda and allies ""CelegansGoldsteinLabUNC.jpg


>529 mya
"Spiralia

"Gnathifera


"Rotifera and allies ""Bdelloid Rotifer (cropped).jpg



"Chaetognatha ""Chaetoblack.png



"Platytrochozoa


"Platyhelminthes and allies ""Sorocelis reticulosa.jpg


"Lophotrochozoa


"Mollusca ""Grapevinesnail 01.jpg



"Annelida and allies ""Polychaeta (no).JPG


550 mya
580 mya

610 mya
650 mya
Triploblasts
680 mya


760 mya
950 mya

Non-bilaterian animals[edit]

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

Several animal phyla lack bilateral symmetry. Among these, the sponges (Porifera) probably diverged first, representing the oldest animal phylum.[104] Sponges lack the complex organization found in most other animal phyla;[105] their cells are differentiated, but in most cases not organised into distinct tissues.[106] They typically feed by drawing in water through pores.[107]

The Ctenophora (comb jellies) and Cnidaria (which includes "jellyfish, "sea anemones, and corals) are radially symmetric and have digestive chambers with a single opening, which serves as both mouth and anus.[108] Animals in both phyla have distinct tissues, but these are not organised into "organs.[109] They are "diploblastic, having only two main germ layers, ectoderm and endoderm.[110] The tiny "placozoans are similar, but they do not have a permanent digestive chamber.[111][112]

Bilaterian animals[edit]

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Idealised "bilaterian body plan.[c] With a cylindrical body and a direction of movement the animal has head and tail ends. Sense organs and mouth form the "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. The body is "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. Animals with this bilaterally symmetric "body plan have a head end (anterior) and a tail end (posterior) as well as a back (dorsal) and a belly (ventral); therefore they also have a left side and a right side.[113][114]

Having a front end means that this part of the body encounters stimuli, such as food, favouring "cephalisation, the development of a head with "sense organs and a mouth. Many bilaterians have a combination of circular "muscles that constrict the body, making it longer, and an opposing set of longitudinal muscles, that shorten the body;[114] these enable soft-bodied animals with a "hydrostatic skeleton to move by "peristalsis.[115] They also have a gut that extends through the basically cylindrical body from mouth to anus. Many bilaterian phyla have primary "larvae which swim with "cilia and have an apical organ containing sensory cells. However, there are exceptions to each of these characteristics; for example, adult echinoderms are radially symmetric (unlike their larvae), while some "parasitic worms have extremely simplified body structures.[113][114]

Genetic studies have considerably changed zoologists' understanding of the relationships within the Bilateria. Most appear to belong to two major lineages, the "protostomes and the "deuterostomes.[116] The basalmost bilaterians are the "Xenacoelomorpha.[117][118][119]

Protostomes and deuterostomes[edit]

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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.[120] 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.[121][122] 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.[123]

The main deuterostome phyla are the Echinodermata and the Chordata.[124] Echinoderms are exclusively marine and include "starfish, "sea urchins, and "sea cucumbers.[125] The chordates are dominated by the "vertebrates (animals with "backbones),[126] which consist of "fishes, "amphibians, "reptiles, "birds, and "mammals.[127] The deuterostomes also include the "Hemichordata (acorn worms).[128][129]

Ecdysozoa[edit]
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"Ecdysis: a "dragonfly has emerged from its dry "exuviae and is expanding its wings. Like other "arthropods, its body is "divided into segments.

The Ecdysozoa are protostomes, named after their shared "trait of "ecdysis, growth by moulting.[130] They include the largest animal phylum, the Arthropoda, which contains insects, spiders, crabs, and their kin. All of these have a body divided into "repeating segments, typically with paired appendages. Two smaller phyla, the "Onychophora and "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;[131] some are important parasites.[132] 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.[133]

Spiralia[edit]
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"Spiral cleavage in a sea snail embryo

The Spiralia are a large group of protostomes that develop by spiral cleavage in the early embryo.[134] The Spiralia's phylogeny has been disputed, but it contains a large clade, the superphylum "Lophotrochozoa, and smaller groups of phyla such as the "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.[135][136]

The Lophotrochozoa includes the "molluscs, "annelids, "brachiopods, "nemerteans, "bryozoa and "entoprocts.[135][137][138] The molluscs, the second-largest animal phylum by number of described species, includes "snails, "clams, and "squids, while the annelids are the segmented worms, such as "earthworms, "lugworms, and "leeches. These two groups have long been considered close relatives because they share "trochophore larvae.[139][140]

History of classification[edit]

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"Jean-Baptiste de Lamarck led the creation of a modern classification of invertebrates, breaking up Linnaeus's "Vermes" into 9 phyla by 1809.[141]

In the "classical era, Aristotle "divided animals,[d] based on his own observations, into those with blood (roughly, the vertebrates) and those without. The animals were then "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.[142]

In 1758, "Carl Linnaeus created the first hierarchical classification in his "Systema Naturae.[143] In his original scheme, the animals were one of three kingdoms, divided into the classes of "Vermes, "Insecta, "Pisces, "Amphibia, "Aves, and "Mammalia. Since then the last four have all been subsumed into a single phylum, the "Chordata, while his Insecta (which included the crustaceans and arachnids) and Vermes have been renamed or broken up. The process was begun in 1793 by "Jean-Baptiste de Lamarck, who called the Vermes une espèce de chaos (a sort of chaos)[e] and split the group into three new phyla, worms, echinoderms, and polyps (which contained corals and jellyfish). By 1809, in his "Philosophie Zoologique, Lamarck had created 9 phyla apart from vertebrates (where he still had 4 phyla: mammals, birds, reptiles, and fish) and molluscs, namely "cirripedes, annelids, crustaceans, arachnids, insects, worms, "radiates, polyps, and "infusorians.[141]

In his 1817 "Le Règne Animal, "Georges Cuvier used "comparative anatomy to group the animals into four embranchements ("branches" with different body plans, roughly corresponding to phyla), namely vertebrates, molluscs, articulated animals (arthropods and annelids), and zoophytes (echinoderms, cnidaria and other forms).[145] 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.[146]

In 1874, "Ernst Haeckel divided the animal kingdom into two subkingdoms: Metazoa (multicellular animals, with five phyla: coelenterates, echinoderms, articulates, molluscs, and vertebrates) and Protozoa (single-celled animals), including a sixth animal phylum, sponges.[147][146] The protozoa were later moved to the former kingdom "Protista, leaving only the Metazoa as a synonym of Animalia.[148]

In human culture[edit]

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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.[149][150] Marine fish of many species are "caught commercially for food. A smaller number of species are "farmed commercially.[149][151][152] Invertebrates including "cephalopods, "crustaceans, and "bivalve or "gastropod molluscs are hunted or farmed for food.[153] Chickens, cattle, sheep, pigs and other animals are raised as livestock for meat across the world.[150][154][155] Animal fibres such as wool are used to make textiles, while animal "sinews have been used as lashings and bindings, and leather is widely used to make shoes and other items. Animals have been hunted and farmed for their fur to make items such as coats and hats.[156][157] Dyestuffs including "carmine ("cochineal),[158][159] "shellac,[160][161] and "kermes[162][163] have been made from the bodies of insects. "Working animals including cattle and horses have been used for work and transport from the first days of agriculture.[164]

Animals such as the fruit fly "Drosophila melanogaster serve a major role in science as "experimental models.[165][166][167][168] Animals have been used to create "vaccines since their discovery in the 18th century.[169] Some medicines such as the cancer drug "Yondelis are based on "toxins or other molecules of animal origin.[170]

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A "gun dog retrieving a duck during a hunt

People have used "hunting dogs to help chase down and retrieve animals,[171] and "birds of prey to catch birds and mammals,[172] while tethered "cormorants have been "used to catch fish.[173] "Poison dart frogs have been used to poison the tips of "blowpipe darts.[174][175] A wide variety of animals are kept as pets, from invertebrates such as tarantulas and octopuses, insects including "praying mantises,[176] reptiles such as "snakes and "chameleons,[177] and birds including "canaries, "parakeets and "parrots[178] all finding a place. However, the most kept pet species are mammals, namely "dogs, "cats, and "rabbits.[179][180][181] There is a tension between the role of animals as companions to humans, and their existence as "individuals with rights of their own.[182] A wide variety of terrestrial and aquatic animals are hunted "for sport.[183]

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Artistic vision: "Still Life with "Lobster and "Oysters by "Alexander Coosemans, c. 1660

Animals have been the "subjects of art from the earliest times, both historical, as in "Ancient Egypt, and prehistoric, as in the "cave paintings at Lascaux. Major animal paintings include "Albrecht Dürer's 1515 "The Rhinoceros, and "George Stubbs's c. 1762 horse portrait "Whistlejacket.[184] "Insects, birds and mammals play roles in literature and film,[185] such as in giant bug movies.[186][187][188] Animals including "insects[189] and mammals[190] feature in mythology and religion. In both Japan and Europe, a "butterfly was seen as the personification of a person's soul,[189][191][192] while the "scarab beetle was sacred in ancient Egypt.[193] Among the mammals, "cattle,[194] "deer,[190] "horses,[195] "lions,[196] "bats[197] and "wolves[198] are the subjects of myths and worship. The "signs of the Western and "Chinese zodiacs are based on animals.[199][200]

See also[edit]

Notes[edit]

  1. ^ 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).[65]
  2. ^ Not including parasitoids.[61]
  3. ^ Compare ""File:Annelid redone w white background.svg for a more specific and detailed model of a particular phylum with this general body plan.
  4. ^ In his "History of Animals and "Parts of Animals.
  5. ^ The prefix une espèce de is pejorative.[144]

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