Animals first appear 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 became clearly established 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. 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 period. (Full article...)
Entries here consist of Good and Featured articles, which meet a core set of high editorial standards.
The jaguar (Panthera onca) is a large cat species and the only living member of the genus Panthera that is native to the Americas. With a body length of up to 1.85 m (6 ft 1 in) and a weight of up to 158 kg (348 lb), it is the biggest cat species in the Americas and the third largest in the world. Its distinctively marked coat features pale yellow to tan colored fur covered by spots that transition to rosettes on the sides, although a melanistic black coat appears in some individuals. The jaguar's powerful bite allows it to pierce the carapaces of turtles and tortoises, and to employ an unusual killing method: it bites directly through the skull of mammalianprey between the ears to deliver a fatal blow to the brain.
Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquaticinvertebrate 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. 5,869living 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 has been described in four genera; Aethozooides, Aethozoon, Franzenella and Monobryozoon). The latter having a statocyst-like organ with a supposed excretory function. (Full article...)
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.
A soybean cyst nematode (Heterodera glycines), together with an egg, as viewed through a low-temperature scanning electron microscope at 1000x magnification. This nematode infects the roots of soybeans, and the female nematode eventually becomes a cyst. Infection causes various symptoms that may include chlorosis of the leaves and stems, root necrosis, loss in seed yield and suppression of root and shoot growth.
The paddyfield pipit (Anthus rufulus) is a passerine bird in the family Motacillidae, comprising pipits, longclaws and wagtails. About 15 cm (6 in) in length and native to southern Asia, its plumage in both sexes is greyish-brown above and paler yellowish-brown below, with dark streaking on the breast. A bird of open country, pasture and cultivated fields, it sometimes makes short flights, but mostly runs on the ground, foraging for insects and other small invertebrates. The paddyfield pipit builds its cup-shaped nest in a concealed location on the ground, and may have two or more broods in a year. This A. r. rufulus individual was photographed in Kanha Tiger Reserve, in the Indian state of Madhya Pradesh.
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.
A lateral (left side) anatomical diagram of an adult-stage nematode hermaphroditeCaenorhabditis elegans (full size) with emphasis on the digestive and reproductive systems. C. elegans is a free-living, transparent nematode (roundworm) which measures about 1 millimetre (0.039 in) in length. The hermaphrodite form, as seen here, is the most common, although a male form is also found. When self-inseminated, the species will lay about 300 eggs, but when the hermaphrodite is inseminated by a male, the number of progeny can exceed 1,000.
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.
Brittle stars, serpent stars, or ophiuroids (from Latin ophiurus 'brittle star'; from Ancient Greekὄφις (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...)
Representative dinosaurs of the Hadrosauroideasuperfamily. The familyHadrosauridae contains the dinosaurs commonly known as "duck-billed" dinosaurs. They were ubiquitous herbivores during the Cretaceous period, and prey to theropoda such as Tyrannosaurus. The individual drawings represent typical genera. All these groups were alive in the late Cretaceous, and are generally known only from a single fossil site. Animals are shown to scale.
The coconut octopus (Amphioctopus marginatus) is a medium-sized cephalopod found in tropical waters of the western Pacific Ocean. It commonly preys upon shrimp, crabs, and clams, and displays unusual behaviour, including bipedal walking and gathering and using coconut shells and seashells for shelter.
A cross section of a post-clitellum segment of an annelid (ringed worm); almost all segments of an annelid contain the same set of organs and parts, a pattern called metamerism. Annelids have no lungs, but rather exchange carbon dioxide and oxygen directly through the moist skin when blood reaches the extremely fine capillaries of the body walls; a dry worm cannot breathe and will die of suffocation. The worm's red blood, which does not consist of platelets or red cells but mostly of a liquid containing suspended hemoglobin, makes a circuit up and down the animal in its closed circulatory systems.
A female Calliope Hummingbird (Stellula calliope), the smallest bird found in Canada and the United States, feeding insects to chicks. Found mostly in western North America (although vagrants have been found in New York and Connecticut), it is migratory and winters in southwestern Mexico.
The Osprey (Pandion haliaetus) is a medium large raptor which is a specialist fish-eater with a worldwide distribution. It is often known by other colloquial names such as Fish Hawk, Sea Hawk or Fish Eagle.
The Osprey is particularly well adapted to its diet, with reversible outer toes, closable nostrils to keep out water during dives, and backwards facing scales on the talons which act as barbs to help catch fish.
The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, platy, meaning "flat" and ἕλμινς (root: ἑλμινθ-), helminth-, meaning "worm") are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates. Being acoelomates (having no body cavity), and having no specialised circulatory and respiratoryorgans, 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...)
The brown pelican (Pelecanus occidentalis) is a bird of the pelican family, Pelecanidae, one of three species found in the Americas and one of two that feed by diving into water. This photograph shows a juvenile brown pelican gliding over the Pacific Ocean at Bodega Head, California.
After hatching, the pelican chicks are fed on regurgitated predigested fish and take about two months to fledge. When they leave the nest, they are at first unable to fly and take wing several weeks later. When the parents cease to feed them, some six months later, each will have consumed around 70 kg (150 lb) of fish. The juvenile brown pelican does not acquire adult plumage until three years of age, when the feathers on the neck become paler, the upperparts striped, the wing feathers grayer, and the belly acquires dark spots.
The bird-cherry ermine (Yponomeuta evonymella) is a species of moth in the family Yponomeutidae, native to Europe and parts of Asia. The caterpillars are gregarious and feed on the leaves of the bird cherry tree, forming silken webbing for their own protection. They create further webbing on the trunk and near the base of the tree, which hides them as they pupate. This photograph shows one of many bird-cherry ermine caterpillar nests on a tree in Lahemaa National Park, Estonia. In some years, they are so numerous that they can completely strip a tree of its foliage.
Entries here consist of Good and Featured articles, which meet a core set of high editorial standards.
Manx shearwaters can fly straight home when released, navigating thousands of miles over land or sea.
Animal navigation is the ability of many animals to find their way accurately without maps or instruments. Birds such as the Arctic tern, insects such as the monarch butterfly and fish such as the salmon regularly migrate thousands of miles to and from their breeding grounds, and many other species navigate effectively over shorter distances.
Dead reckoning, navigating from a known position using only information about one's own speed and direction, was suggested by Charles Darwin in 1873 as a possible mechanism. In the 20th century, Karl von Frisch showed that honey bees can navigate by the Sun, by the polarization pattern of the blue sky, and by the Earth's magnetic field; of these, they rely on the Sun when possible. William Tinsley Keeton showed that homing pigeons could similarly make use of a range of navigational cues, including the Sun, Earth's magnetic field, olfaction and vision. Ronald Lockley demonstrated that a small seabird, the Manx shearwater, could orient itself and fly home at full speed, when released far from home, provided either the Sun or the stars were visible. (Full article...)
...that Caecillians, an order of amphibians resembling snakes or worms, possess a pair of tentacles, located between their eyes and nostrils which are probably used for olfaction?
The following are images from various animal-related articles on Wikipedia.
Image 1The blue whale is the largest animal that has ever lived; it can be up to 33.6 metres (110 ft) long. (from Animal)
Image 2Kelp gull chicks peck at red spot on mother's beak to stimulate the regurgitating reflex. (from Zoology)
Image 3The 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 4Linnaeus's table of the animal kingdom from the first edition of Systema Naturae (1735) (from Zoology)
Image 9Simplified schematic of an island's fauna – all its animal species, highlighted in boxes (from Fauna)
Image 10Non-bilaterians include sponges (centre) and corals (background). (from Animal)
Image 11Fish and frog melanophores are cells that can change colour by dispersing or aggregating pigment-containing bodies. (from Animal coloration)
Image 12A 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 13Squid chromatophores appear as black, brown, reddish and pink areas in this micrograph. (from Animal coloration)
Image 14The black and yellow warning colours of the cinnabar moth caterpillar, Tyria jacobaeae, are avoided by some birds. (from Animal coloration)
Image 17Idealised bilaterian 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 37A 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 41The bilaterian gut develops in two ways. In many protostomes, the blastopore develops into the mouth, while in deuterostomes it becomes the anus. (from Animal)
The following table lists estimated numbers of described extant species for the animal groups with the largest numbers of species,[1] along with their principal habitats (terrestrial, fresh water,[2] and marine),[3] and free-living or parasitic ways of life.[4] 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.[5] 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.[6][7][a]
^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).[8]
^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. PMID28938083. S2CID23755007. Stork notes that 1m insects have been named, making much larger predicted estimates.
^ abcdNicol, David (June 1969). "The Number of Living Species of Molluscs". Systematic Zoology. 18 (2): 251–254. doi:10.2307/2412618. JSTOR2412618.
^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. S2CID38784755.
.jpg)
.jpg)
_caterpillars.jpg)
.jpg)
.png)
.JPG)
_Naggar,_Himachal_Pradesh,_2013_(cropped).JPG)
.jpg){kind=small}
.jpg)
Commons
Wikibooks
Wikidata
Wikinews
Wikiquote
Wikisource
Wikispecies
Wikiversity
Wiktionary
