Portal:Animals

Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (/ˌænɪˈmeɪliə/). 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. Animals form a clade, meaning that they arose from a single common ancestor. Over 1.5 million living animal species have been described, of which around 1.05 million are insects, over 85,000 are molluscs, and around 65,000 are vertebrates. It has been estimated there are as many as 7.77 million animal species on Earth. Animal body lengths range from 8.5 μm (0.00033 in) to 33.6 m (110 ft). They have complex 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 behaviour is known as ethology.

The animal kingdom is divided into five major clades, namely Porifera, Ctenophora, Placozoa, Cnidaria and Bilateria. Most living animal species belong to the clade Bilateria, a highly proliferative clade whose members have a bilaterally symmetric and significantly cephalised body plan, and the vast majority of bilaterians belong to two large clades: the protostomes, which includes organisms such as arthropods, molluscs, flatworms, annelids and nematodes; and the deuterostomes, which include echinoderms, hemichordates and chordates, the latter of which contains the vertebrates. The much smaller basal phylum Xenacoelomorpha have an uncertain position within Bilateria.

Animals first appeared in the fossil record in the late Cryogenian period and diversified in the subsequent Ediacaran period in what is known as the Avalon explosion. Earlier evidence of animals is still controversial; the sponge-like organism Otavia has been dated back to the Tonian period at the start of the Neoproterozoic, but its identity as an animal is heavily contested. Nearly all modern animal phyla first appeared in the fossil record as marine species during the Cambrian explosion, which began around 539 million years ago (Mya), and most classes during the Ordovician radiation 485.4 Mya. Common to all living animals, 6,331 groups of genes have been identified that may have arisen from a single common ancestor that lived about 650 Mya during the Cryogenian period. (Full article...)

Zoology (UK: /zuˈɒlədʒi/ zoo-OL-ə-jee, US: /zoʊˈɒlədʒi/ zoh-OL-ə-jee) 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. Zoology is one of the primary branches of biology. The term is derived from Ancient Greek ζῷον, zōion ('animal'), and λόγος, logos ('knowledge', 'study'). (Full article...)

Entries here consist of Good and Featured articles, which meet a core set of high editorial standards.

A red-bellied black snake in Lamington National Park, Queensland

The red-bellied black snake (Pseudechis porphyriacus) is a species of venomous snake in the family Elapidae, indigenous to Australia. Originally described by George Shaw in 1794 as a species new to science, it is one of eastern Australia's most commonly encountered snakes. Averaging around 1.25 m (4 ft 1 in) in length, it has glossy black upperparts, bright red or orange flanks, and a pink or dull red belly. It is not aggressive and generally retreats from human encounters, but will defend itself if provoked. Although its venom can cause significant illness, no deaths have been recorded from its bite, which is less venomous than other Australian elapid snakes. The venom contains neurotoxins, myotoxins, and coagulants and has haemolytic properties. Victims can also lose their sense of smell.

Common in woodlands, forests, swamplands, along river banks and waterways, the red-bellied black snake often ventures into nearby urban areas. It forages in bodies of shallow water, commonly with tangles of water plants and logs, where it hunts its main prey item, frogs, as well as fish, reptiles, and small mammals. The snake is a least-concern species according to the IUCN, but its numbers are thought to be declining due to habitat fragmentation and decline of frog populations. (Full article...)

List of selected animal articles

Image 1
Atlantic spadefish
Photo: Matthew Hoelscher, Papa Lima Whiskey
The Atlantic spadefish is a species of marine fish endemic to the shallow waters off the coast of the southeastern United States and in the Caribbean Sea. They are similar in appearance to fresh water angelfish, but much larger, reaching up to three feet (0.9 m) in length. Due to their reputation as strong fighters, they are popular game fish, especially during the summer months when they are most active.
Image 2
Leopard seal
Photograph: Godot13
The leopard seal (Hydrurga leptonyx), also known as the sea leopard, is the second largest species of seal in the Antarctic, after the southern elephant seal. Its only natural predators are the killer whale and possibly the elephant seal. It feeds on a wide range of prey including cephalopods, other pinnipeds, krill, birds and fish. Together with the Ross seal, the crabeater seal and the Weddell seal, it is part of the tribe of lobodontini seals.

This image shows a leopard seal in the Antarctic Sound in 2016. See also the same seal yawning.
Image 3
Flatworms
Credit: Ernst Haeckel, Kunstformen der Natur (1904)
Platyhelminthes (from the Greek πλατύ, platy, meaning "flat" and ἕλμινς (root: ἑλμινθ-), helminth-, meaning "worm") is a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates commonly called flatworms or flat worms. Being acoelomates (having no body cavity), and having no specialised circulatory and respiratory organs, they are restricted to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, the food can not be processed continuously. (Full article...)
Image 4
Sperm Whale
Photograph: Gabriel Barathieu
The sperm whale is the largest toothed animal on Earth. The species was hunted extensively by humans throughout history, until protected by a worldwide moratorium on whaling starting in 1985–86.
Image 5
Brittle star
Credit: Hans Hillewaert
Brittle stars, serpent stars, or ophiuroids (from Latin ophiurus 'brittle star'; from Ancient Greek ὄφις (óphis) 'serpent' and οὐρά (ourá) 'tail'; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the sea floor using their flexible arms for locomotion. The ophiuroids generally have five long, slender, whip-like arms which may reach up to 60 cm (24 in) in length on the largest specimens. (Full article...)
Image 6
Rotifers
Credit: Frank Fox
The rotifers (/ˈroʊtɪfərz/, from Latin rota 'wheel' and -fer 'bearing'), sometimes called wheel animals or wheel animalcules, make up a phylum (Rotifera /roʊˈtɪfərə/) of microscopic and near-microscopic pseudocoelomate animals. (Full article...)
Image 7
Black-crowned night heron
Photograph: Alain Carpentier
A black-crowned night heron (Nycticorax nycticorax) feeding on a fish in the shallows of the Chêne River in Montreal, Quebec. These widespread ambush predators average 64 cm (25 in) in length.
Image 8
Nembrotha cristata
Photograph: Steve Childs
Nembrotha cristata is a colourful species of sea slug. This nudibranch, a marine gastropod in the family Polyceridae, lives on rocks or coral reefs in the tropical Indo-West Pacific Ocean. This species of sea slug is black with green markings. Adults reach lengths of around 50 mm.
Image 9
Haliotis laevigata
Photograph credit: H. Zell
Haliotis laevigata is a species of marine mollusc in the family Haliotidae, endemic to Tasmania and the southern and western coasts of Australia. This picture shows five views of a green H. laevigata shell, 7.5 centimetres (3.0 in) in length. The holes in the shell, characteristic of abalones, are respiratory apertures for venting water from the gills and for releasing sperm and eggs into the water column.
Image 10
Liguus virgineus
Photograph: H. Zell
Liguus virgineus, also known as the candy cane snail, is a species of snail in the family Orthalicidae. It is native to the Caribbean island of Hispaniola, in the nations of Haiti and the Dominican Republic. There have also been at least three reports of living specimens being found in the Florida Keys of the United States. The snail lives on trees and feeds on moss, fungi and microscopic algae covering the bark.
Image 11
Coral
Photograph: Toby Hudson
Corals are marine invertebrates that typically live in compact colonies of many identical individual polyps. Each polyp is a sac-like animal typically only a few millimeters in diameter and a few centimeters in length. Corals are major contributors to the physical structure of the coral reefs such as the Great Barrier Reef, where this photograph was taken. Coral reefs are under threat globally from ocean acidification and climate change.
Image 12
Bryozoa
Credit: Ernst Haeckel, Kunstformen der Natur (1904)
Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about 0.5 millimetres (1⁄64 in) long, they have a special feeding structure called a lophophore, a "crown" of tentacles used for filter feeding. Most marine bryozoans live in tropical waters, but a few are found in oceanic trenches and polar waters. The bryozoans are classified as the marine bryozoans (Stenolaemata), freshwater bryozoans (Phylactolaemata), and mostly-marine bryozoans (Gymnolaemata), a few members of which prefer brackish water. 5,869 living species are known. Originally all of the crown group Bryozoa were colonial, but as an adaptation to a mesopsammal (interstitial spaces in marine sand) life or to deep-sea habitats, secondarily solitary forms have since evolved. Solitary species have been described in four genera; (Aethozooides, Aethozoon, Franzenella and Monobryozoon). The latter having a statocyst-like organ with a supposed excretory function. (Full article...)
Image 13
Redeye gaper
Photo: Steve Ross, NOAA Office of Ocean Exploration
The redeye gaper (Chaunax stigmaeus) is a sedentary species of anglerfish native to deep waters in the western North Atlantic from the Georges Bank off New England southward to the Blake Plateau off South Carolina. It is a sedentary ambush predator that spends most of its time resting on the sea floor on its pectoral and pelvic fins, moving only to capture prey or avoid predators.
Image 14
Sponges
Credit: Twilight Zone Expedition Team 2007, NOAA-OE
Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (/pəˈrɪfərəˌ pɔː-/; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and are one of the most ancient members of macrobenthos, with many historical species being important reef-building organisms. (Full article...) Included are the yellow tube sponge, Aplysina fistularis, the purple vase sponge, Niphates digitalis, the red encrusting sponge, Spirastrella coccinea, and the gray rope sponge, Callyspongia sp.
Image 15
Lymantria dispar dispar
Photograph: Didier Descouens
A caterpillar of Lymantria dispar dispar, also known as the gypsy moth. First described by Carl Linnaeus in 1758, the gypsy moth is found throughout Eurasia, where it is considered a pest. The larvae emerge from egg masses in the spring, and then are dispersed by the wind and begin feeding on leaves. They are initially diurnal, but become nocturnal after their fourth molting.
Image 16
Calcareous sponge
Image credit: Ernst Haeckel
Plate 5 from Ernst Haeckel's Kunstformen der Natur, showing a variety of calcareous sponges, a class of about 400 marine sponges that are found mostly in shallow tropical waters worldwide. Calcareous sponges vary from radially symmetrical vase-shaped body types to colonies made up of a meshwork of thin tubes, or irregular massive forms. The skeleton has either a mesh or honeycomb structure.
Image 17
Alitta succinea
Photograph: Hans Hillewaert
The common clam worm (Alitta succinea) is a widely distributed species of marine polychaete worm. The photograph shows an epitoke specimen, the worm having turned into a form capable of reproduction. After releasing its sperm or eggs, the animal will die.
Image 18
Thysanozoon nigropapillosum
Photograph credit: Betty Wills
Thysanozoon nigropapillosum, the yellow-spotted flatworm, is a species of marine flatworm in the family Pseudocerotidae. The species is native to the tropical Indo-Pacific region, where it lives in shallow reef habitats. Flatworms are hermaphrodites, each being able to act as either male or female. As a donor of sperm, it can grip the margin of the recipient's body, using its two penises in a chopstick-like manner, and deposit sperm on the surface of the skin of the recipient, even while it is actively swimming.

This picture shows a yellow-spotted flatworm photographed in Manta Ray Bay, on the island of Yap in the Federated States of Micronesia. The flatworm is seen swimming to the right at a depth of 12 metres (40 ft) by undulating the margins of its body. The pseudotentacles at the front have simple eyes and sensory receptors to enable the flatworm to find tunicates on which it feeds.
Image 19
Sexual dimorphism
Photograph credit: Paolo Costa Baldi
Sexual dimorphism is the condition where the two sexes of the same species exhibit different characteristics. Differences may include secondary sex characteristics, size, weight, color, or markings, as well as behavioral and cognitive differences. In the butterfly species Colias dimera (also known as the Dimera sulphur), seen here mating in Venezuela, the male on the right is a brighter shade of yellow than the female.
Image 20
Caesio teres
Photograph: Nick Hobgood
Caesio teres is a pelagic marine fish belonging to the family Caesionidae. Widely distributed throughout the tropical waters of the Indian and western Pacific Ocean, this species feeds on zooplankton. It can grow to 40 cm (16 in) in length.

Entries here consist of Good and Featured articles, which meet a core set of high editorial standards.

Ursidae is a family of mammals in the order Carnivora, which includes the giant panda, brown bear, and polar bear, and many other extant or extinct mammals. A member of this family is called a bear or an ursid. They are widespread across the Americas and Eurasia. Bear habitats are generally forests, though some species can be found in grassland and savana regions, and the polar bear lives in arctic and aquatic habitats. Most bears are 1.2–2 m (4–7 ft) long, plus a 3–20 cm (1–8 in) tail, though the polar bear is 2.2–2.44 m (7–8 ft) long, and some subspecies of brown bear can be up to 2.8 m (9 ft). Weights range greatly from the sun bear, which can be as low as 35 kg (77 lb), to the polar bear, which can be as high as 726 kg (1,600 lb). Population sizes vary, with six species classified as vulnerable with populations as low as 500, while the brown bear has a population of over 100,000 and the American black bear around 800,000. Many bear species primarily eat specific foods, such as seals for the polar bear or termites and fruit for the sloth bear, but with the exception of the giant panda, which exclusively eats bamboo, ursids are omnivorous when necessary. No ursid species have been domesticated, though some bears have been trained for entertainment.

The eight species of Ursidae are split into five genera in three subfamilies: the monotypic Ailuropodinae, the panda bears; Tremarctinae, the short-faced bears; and Ursinae, containing all other extant bears. Extinct species have also been placed into all three extant subfamilies, as well as three extinct ones: Agriotheriinae, Hemicyoninae, and Ursavinae. Over 100 extinct Ursidae species have been found, though due to ongoing research and discoveries the exact number and categorization is not fixed. (Full article...)

List of selected articles

...that six new species of marine slugs in the genus Phyllodesmium (Sp. kabiranum pictured) have been described in the last two years?
...that Maui's dolphin is the most endangered species of dolphin in the world, with only about 110 left?
...that the land snail Euglandina rosea is a significant threat to Hawaiian freshwater snail known as Newcomb's snail (Erinna newcombi), because the predatory Euglandina is able to hunt Erinna under water?
...that the body of the "X-ray fish" (Pristella maxillaris ) is so transparent that it is possible to see its backbone?
...that even though the lancelets are classified as chordates, they lack a true backbone and well-defined head?

The following are images from various animal-related articles on Wikipedia.

Image 1A clade representation of seven dog breeds in relation to wolves. (from Zoology)
Image 2Siberian tiger (from Mammalogy)
Image 3In Roseate Spoonbills 1905–1909, Abbott Handerson Thayer tried to show that even the bright pink of these conspicuous birds had a cryptic function. (from Animal coloration)
Image 4The Spiralia develop with spiral cleavage in the embryo, as here in a sea snail. (from Animal)
Image 5Idealised nephrozoan body plan. With an elongated 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. (from Animal)
Image 6Animal anatomical engraving from Handbuch der Anatomie der Tiere für Künstler. (from Zoology)
Image 7A praying mantis in deimatic or threat pose displays conspicuous patches of colour to startle potential predators. This is not warning coloration as the insect is palatable. (from Animal coloration)
Image 8Non-bilaterians include sponges (centre) and corals (background). (from Animal)
Image 9Animals are unique in having the ball of cells of the early embryo (1) develop into a hollow ball or blastula (2). (from Animal)
Image 10Examples of fauna in Olleros de Tera (Spain) (from Fauna)
Image 11Bright coloration of orange elephant ear sponge, Agelas clathrodes signals its bitter taste to predators (from Animal coloration)
Image 12The brilliant iridescent colours of the peacock's tail feathers are created by Structural coloration. (from Animal coloration)
Image 13Linnaeus's table of the animal kingdom from the first edition of Systema Naturae (1735) (from Zoology)
Image 14Predators, such as this ultramarine flycatcher (Ficedula superciliaris), feed on other animals. (from Animal)
Image 15A camouflaged orange oak leaf butterfly, Kallima inachus (centre) has protective resemblance. (from Animal coloration)
Image 16Kelp gull chicks peck at red spot on mother's beak to stimulate the regurgitating reflex. (from Zoology)
Image 17Artistic vision: Still Life with Lobster and Oysters by Alexander Coosemans, c. 1660 (from Animal)
Image 18Simplified schematic of an island's fauna – all its animal species, highlighted in boxes (from Fauna)
Image 19The red pigment in a flamingo's plumage comes from its diet of shrimps, which get it from microscopic algae. (from Animal coloration)
Image 20Conrad Gessner (1516–1565). His Historiae animalium is considered the beginning of modern zoology. (from Zoology)
Image 21Warning coloration of the skunk in Edward Bagnall Poulton's The Colours of Animals, 1890 (from Animal coloration)
Image 22The black and yellow warning colours of the cinnabar moth caterpillar, Tyria jacobaeae, are avoided by some birds. (from Animal coloration)
Image 23The microscopic cave snail Zospeum tholussum, found at depths of 743 to 1,392 m (2,438 to 4,567 ft) in the Lukina Jama–Trojama cave system of Croatia, is completely blind with a translucent shell (from Fauna)
Image 24Jean-Baptiste de Lamarck led the creation of a modern classification of invertebrates, breaking up Linnaeus's "Vermes" into 9 phyla by 1809. (from Animal)
Image 25Papuan, Australian and New Zealand fauna. This image was likely first published in the first edition (1876–1899) of the Nordisk familjebok. (from Fauna)
Image 26Cleaner wrasse signals its cleaning services to a big eye squirrelfish (from Animal coloration)
Image 27Side of zebrafish shows how chromatophores (dark spots) respond to 24 hours in dark (above) or light (below). (from Animal coloration)
Image 28A brilliantly-coloured oriental sweetlips fish (Plectorhinchus vittatus) waits while two boldly-patterned cleaner wrasse (Labroides dimidiatus) pick parasites from its skin. The spotted tail and fin pattern of the sweetlips signals sexual maturity; the behaviour and pattern of the cleaner fish signal their availability for cleaning service, rather than as prey (from Animal coloration)
Image 29The bilaterian gut develops in two ways. In many protostomes, the blastopore develops into the mouth, while in deuterostomes it becomes the anus. (from Animal)
Image 30A venomous coral snake uses bright colours to warn off potential predators. (from Animal coloration)
Image 31Male Goldie's bird-of-paradise displays to a female (from Animal coloration)
Image 32Squid chromatophores appear as black, brown, reddish and pink areas in this micrograph. (from Animal coloration)
Image 33Fish and frog melanophores are cells that can change colour by dispersing or aggregating pigment-containing bodies. (from Animal coloration)
Image 34Sexual reproduction is nearly universal in animals, such as these dragonflies. (from Animal)
Image 35The blue whale is the largest animal that has ever lived; it can be up to 33.6 metres (110 ft) long. (from Animal)
Image 36Myxozoans such as Myxobolus cerebralis are single-celled parasites, never more than 20 μm across. (from Animal)
Image 37This frog changes its skin colour to control its temperature. (from Animal coloration)
Image 38Robert Hooke's Micrographia (from Animal coloration)
Image 39A flower mantis, Hymenopus coronatus, uses special Aggressive mimicry. (from Animal coloration)
Image 40Butterfly wing at different magnifications reveals microstructured chitin acting as diffraction grating. (from Animal coloration)
Image 41A Euplokamis comb jelly is bioluminescent. (from Animal coloration)
Image 42Hydrothermal vent mussels and shrimps (from Animal)
Image 43The hawk-cuckoo resembles a predatory shikra, giving the cuckoo time to lay eggs in a songbird's nest unnoticed (from Animal coloration)
Image 44Sides of beef in a slaughterhouse (from Animal)
Image 45The olm's blood makes it appear pink. (from Animal coloration)
Image 46A gun dog retrieving a duck during a hunt (from Animal)

The following table lists estimated numbers of described extant species for the animal groups with the largest numbers of species, along with their principal habitats (terrestrial, fresh water, and marine), and free-living or parasitic ways of life. 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. 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.

Phylum	No. of Species	Land	Sea	Fresh water	Free- living	Parasitic
Annelids	17,000	Yes (soil)	Yes	1,750	Yes	400
Arthropods	1,257,000	1,000,000 (insects)	>40,000 (Malac- ostraca)	94,000	Yes	>45,000
Bryozoa	6,000		Yes	60–80	Yes
Chordates	65,000 45,000	23,000	13,000	18,000 9,000	Yes	40 (catfish)
Cnidaria	16,000		Yes	Yes (few)	Yes	>1,350 (Myxozoa)
Echinoderms	7,500		7,500		Yes
Molluscs	85,000 107,000	35,000	60,000	5,000 12,000	Yes	>5,600
Nematodes	25,000	Yes (soil)	4,000	2,000	11,000	14,000
Platyhelminthes	29,500	Yes	Yes	1,300	Yes 3,000–6,500	>40,000 4,000–25,000
Rotifers	2,000		>400	2,000	Yes
Sponges	10,800		Yes	200-300	Yes	Yes
Total number of described extant species as of 2013: 1,525,728

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↑ 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).
↑ Not including parasitoids.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 Zhang, Zhi-Qiang (2013-08-30). "Animal biodiversity: An update of classification and diversity in 2013. In: Zhang, Z.-Q. (Ed.) Animal Biodiversity: An Outline of Higher-level Classification and Survey of Taxonomic Richness (Addenda 2013)". Zootaxa. 3703 (1): 5. doi:10.11646/zootaxa.3703.1.3. Archived from the original on 24 April 2019. Retrieved 2 March 2018.
1 2 3 4 5 6 7 8 9 10 Balian, E. V.; Lévêque, C.; Segers, H.; Martens, K. (2008). Freshwater Animal Diversity Assessment. Springer. p. 628. ISBN 978-1-4020-8259-7.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 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.
1 2 3 4 5 6 7 8 Poulin, Robert (2007). Evolutionary Ecology of Parasites. Princeton University Press. p. 6. ISBN 978-0-691-12085-0.
1 2 3 4 Felder, Darryl L.; Camp, David K. (2009). Gulf of Mexico Origin, Waters, and Biota: Biodiversity. Texas A&M University Press. p. 1111. ISBN 978-1-60344-269-5.
↑ "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.
↑ Mora, Camilo; Tittensor, Derek P.; Adl, Sina; Simpson, Alastair G.B.; Worm, Boris (2011-08-23). Mace, Georgina M. (ed.). "How Many Species Are There on Earth and in the Ocean?". PLOS Biology. 9 (8): e1001127. doi:10.1371/journal.pbio.1001127. PMC 3160336. PMID 21886479.
↑ Hebert, Paul D.N.; Ratnasingham, Sujeevan; Zakharov, Evgeny V.; Telfer, Angela C.; Levesque-Beaudin, Valerie; Milton, Megan A.; Pedersen, Stephanie; Jannetta, Paul; deWaard, Jeremy R. (1 August 2016). "Counting animal species with DNA barcodes: Canadian insects". Philosophical Transactions of the Royal Society B: Biological Sciences. 371 (1702): 20150333. doi:10.1098/rstb.2015.0333. PMC 4971185. PMID 27481785.
↑ Stork, Nigel E. (January 2018). "How Many Species of Insects and Other Terrestrial Arthropods Are There on Earth?". Annual Review of Entomology. 63 (1): 31–45. doi:10.1146/annurev-ento-020117-043348. PMID 28938083. S2CID 23755007. Stork notes that 1m insects have been named, making much larger predicted estimates.
↑ Poore, Hugh F. (2002). "Introduction". Crustacea: Malacostraca. Zoological catalogue of Australia. Vol. 19.2A. CSIRO Publishing. pp. 1–7. ISBN 978-0-643-06901-5.
1 2 3 4 Reaka-Kudla, Marjorie L.; Wilson, Don E.; Wilson, Edward O. (1996). Biodiversity II: Understanding and Protecting Our Biological Resources. Joseph Henry Press. p. 90. ISBN 978-0-309-52075-1.
↑ Burton, Derek; Burton, Margaret (2017). Essential Fish Biology: Diversity, Structure and Function. Oxford University Press. pp. 281–282. 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.
1 2 3 4 Nicol, David (June 1969). "The Number of Living Species of Molluscs". Systematic Zoology. 18 (2): 251–254. doi:10.2307/2412618. JSTOR 2412618.
↑ Sluys, R. (1999). "Global diversity of land planarians (Platyhelminthes, Tricladida, Terricola): a new indicator-taxon in biodiversity and conservation studies". Biodiversity and Conservation. 8 (12): 1663–1681. doi:10.1023/A:1008994925673. S2CID 38784755.
1 2 Pandian, T. J. (2020). Reproduction and Development in Platyhelminthes. CRC Press. pp. 13–14. ISBN 9781000054903.
↑ 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.
↑ Morand, Serge; Krasnov, Boris R.; Littlewood, D. Timothy J. (2015). Parasite Diversity and Diversification. Cambridge University Press. p. 44. ISBN 978-1-107-03765-6. Archived from the original on 12 December 2018. Retrieved 2 March 2018.

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[9] 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).

[12] Not including parasitoids.

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[Balian2008-2] 1 2 3 4 5 6 7 8 9 10 Balian, E. V.; Lévêque, C.; Segers, H.; Martens, K. (2008). Freshwater Animal Diversity Assessment. Springer. p. 628. ISBN 978-1-4020-8259-7.

[Hogenboom2016-3] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 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.

[Poulin2007-4] 1 2 3 4 5 6 7 8 Poulin, Robert (2007). Evolutionary Ecology of Parasites. Princeton University Press. p. 6. ISBN 978-0-691-12085-0.

[Felder2009-5] 1 2 3 4 Felder, Darryl L.; Camp, David K. (2009). Gulf of Mexico Origin, Waters, and Biota: Biodiversity. Texas A&M University Press. p. 1111. ISBN 978-1-60344-269-5.

[6] "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.

[Mora2011-7] Mora, Camilo; Tittensor, Derek P.; Adl, Sina; Simpson, Alastair G.B.; Worm, Boris (2011-08-23). Mace, Georgina M. (ed.). "How Many Species Are There on Earth and in the Ocean?". PLOS Biology. 9 (8): e1001127. doi:10.1371/journal.pbio.1001127. PMC 3160336. PMID 21886479.

[8] Hebert, Paul D.N.; Ratnasingham, Sujeevan; Zakharov, Evgeny V.; Telfer, Angela C.; Levesque-Beaudin, Valerie; Milton, Megan A.; Pedersen, Stephanie; Jannetta, Paul; deWaard, Jeremy R. (1 August 2016). "Counting animal species with DNA barcodes: Canadian insects". Philosophical Transactions of the Royal Society B: Biological Sciences. 371 (1702): 20150333. doi:10.1098/rstb.2015.0333. PMC 4971185. PMID 27481785.

[Stork2018-10] Stork, Nigel E. (January 2018). "How Many Species of Insects and Other Terrestrial Arthropods Are There on Earth?". Annual Review of Entomology. 63 (1): 31–45. doi:10.1146/annurev-ento-020117-043348. PMID 28938083. S2CID 23755007. Stork notes that 1m insects have been named, making much larger predicted estimates.

[11] Poore, Hugh F. (2002). "Introduction". Crustacea: Malacostraca. Zoological catalogue of Australia. Vol. 19.2A. CSIRO Publishing. pp. 1–7. ISBN 978-0-643-06901-5.

[Reaka-Kudla1996-13] 1 2 3 4 Reaka-Kudla, Marjorie L.; Wilson, Don E.; Wilson, Edward O. (1996). Biodiversity II: Understanding and Protecting Our Biological Resources. Joseph Henry Press. p. 90. ISBN 978-0-309-52075-1.

[14] Burton, Derek; Burton, Margaret (2017). Essential Fish Biology: Diversity, Structure and Function. Oxford University Press. pp. 281–282. 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.

[Nicol1969-15] 1 2 3 4 Nicol, David (June 1969). "The Number of Living Species of Molluscs". Systematic Zoology. 18 (2): 251–254. doi:10.2307/2412618. JSTOR 2412618.

[16] Sluys, R. (1999). "Global diversity of land planarians (Platyhelminthes, Tricladida, Terricola): a new indicator-taxon in biodiversity and conservation studies". Biodiversity and Conservation. 8 (12): 1663–1681. doi:10.1023/A:1008994925673. S2CID 38784755.

[Pandian-17] 1 2 Pandian, T. J. (2020). Reproduction and Development in Platyhelminthes. CRC Press. pp. 13–14. ISBN 9781000054903.

[18] 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.

[19] Morand, Serge; Krasnov, Boris R.; Littlewood, D. Timothy J. (2015). Parasite Diversity and Diversification. Cambridge University Press. p. 44. ISBN 978-1-107-03765-6. Archived from the original on 12 December 2018. Retrieved 2 March 2018.