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 behaviors is known as ethology.
The elk (pl.: elk or elks; Cervus canadensis), or wapiti, is the second largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. The word "elk" originally referred to the European variety of the moose, Alces alces, but was transferred to Cervus canadensis by North American colonists.
The name "wapiti" is derived from a Shawnee and Cree word meaning "white rump", after the distinctive light fur around the tail region which the animals may fluff-up or raise to signal their agitation or distress to one another, when fleeing perceived threats, or among males courting females and sparring for dominance. A similar trait is seen in other artiodactyl species, like the bighorn sheep, pronghorn and the white-tailed deer, to varying degrees. (Full article...)
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.
Glaucus atlanticus is a species of small, blue sea slug. This pelagic aeolid nudibranch floats upside down, using the surface tension of the water to stay up, and is carried along by the winds and ocean currents. The blue side of their body faces upwards, blending in with the blue of the water, while the grey side faces downwards, blending in with the silvery surface of the sea. G. atlanticus feeds on other pelagic creatures, including the Portuguese man o' war.
Eutropis macularia, the bronze grass skink, is a species of lizard in the skink family, Scincidae, native to South and Southeast Asia. It lives in both deciduous and evergreen forests, in plantations, in grasslands, and in rocky areas with scattered trees. The species is active in both the day and the night, feeding on insects and other invertebrates. This bronze grass skink was photographed on a tree trunk on the island of Don Det in Laos.
The Common Brushtail Possum (Trichosurus vulpecula) is the largest possum species and is perhaps the most widespread mammal in Australia. It grows to about 32–58 cm (13–23 in) in length, with an additional 24–40 cm (9–16 in) for its prehensile tail (seen here hanging below the branch). It is mainly a folivore, but has been known to eat small mammals such as rats. It is common in cities, having adapted well to human habitation.
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...)
An illustration of various Pulmonata (and one predator arthropod in the lower right), an informal group of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. Pulmonata was previously a formal taxon but lost its status as one in 2010. The group includes many land and freshwater families, and several marine families. Most species have a shell, but no operculum, although the group does also include several shell-less slugs. Pulmonates are hermaphroditic, and some groups possess love darts.
The Peacock flounder (Bothus mancus) is a species of lefteye flounder found widely in relatively shallow waters in the Indo-Pacific. This photomontage shows four separate views of the same fish, each several minutes apart, starting from the top left. Over the course of the photos, the fish changes its colors to match its new surroundings, and then finally (bottom right) buries itself in the sand, leaving only the eyes protruding.
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.
Anatomical diagram of an adult female chambered nautilus, the best known species of nautilus, a "living fossil" related to the octopuses. The animal has a primitive brain that forms a ring around its oesophagus, has four gills (all other cephalopods have only two), and can only move shell-first (seemingly "backwards") by pumping water out through its funnel. The shell and tentacles are shown here as shadows.
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.
A macro view of a Gonia capitatafly feeding on honey, showing its proboscis and pedipalps (the two appendages protruding from the proboscis), two types of insect mouthparts. The proboscis actually comprises the labium, a quadrupedal structure, and a sponge-like labellum at the end. Flies eat solid food by secreting saliva and dabbing it over the food item. As the saliva dissolves the food, the solution is then drawn up into the mouth as a liquid. The labellum's surface is covered by minute food channels which form a tube leading to the esophagus, and food is drawn up the channels by capillary action.
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...)
Velodona togata is the only species in the octopus genus Velodona; the genus and species names come from the large membranes that connect its arms. It was first described by Carl Chun in his book Die Cephalopoden (from which this illustration is taken) in 1915. A second subspecies was described by Guy Coburn Robson in 1924.
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.
Entries here consist of Good and Featured articles, which meet a core set of high editorial standards.
Felidae is a family of mammals in the orderCarnivora, colloquially referred to as cats. A member of this family is called a felid. The term "cat" refers both to felids in general and specifically to domestic cats. The characteristic features of cats have evolved to support a carnivorous lifestyle, with adaptations for ambush or stalking and short pursuit hunting. They have slender muscular bodies, strong flexible forelimbs and retractable claws for holding prey, dental and cranial adaptations for a strong bite, and often have characteristic striped or spotted coat patterns for camouflage. (Full article...)
...that the Southern Giant Petrel is the leading predator to the Emperor Penguin, and may be responsible for up to 34% of chick deaths in some colonies?
...that some goats freeze for ten seconds whenever startled due to the genetic condition known as myotonia congenita, and have thus been dubbed "fainting goats"?
The following are images from various animal-related articles on Wikipedia.
Image 1Animals are unique in having the ball of cells of the early embryo (1) develop into a hollow ball or blastula (2). (from Animal)
Image 2A 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 5The 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 38Linnaeus's table of the animal kingdom from the first edition of Systema Naturae (1735) (from Zoology)
Image 39Idealised 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 40Butterfly wing at different magnifications reveals microstructured chitin acting as diffraction grating. (from Animal coloration)
Image 45The 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 49A 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)
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.