A coral "group" is a colony of very manygenetically identical polyps. Each polyp is a sac-like animal typically only a few millimeters in diameter and a few centimeters in height. A set oftentacles surround a central mouth opening. Each polyp excretes anexoskeleton near the base. Over many generations, the colony thus creates a skeleton characteristic of the species which can measure up to several meters in size. Individual colonies grow byasexual reproduction of polyps. Corals also breed sexually byspawning: polyps of the same species releasegametes simultaneously overnight, often around afull moon. Fertilized eggs form planulae, a mobile early form of the coral polyp which, when mature, settles to form a new colony. (Full article...)
Thebrown 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 atBodega Head, California.
After hatching, the pelican chicks are fed onregurgitated 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.
Anatomical diagram of an adult femalechambered nautilus, the best known species ofnautilus, a "living fossil" related to the octopuses. The animal has a primitive brain that forms a ring around itsoesophagus, has four gills (all othercephalopods 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.
Thepaddyfield pipit (Anthus rufulus) is apasserine bird in the familyMotacillidae, comprisingpipits,longclaws andwagtails. 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. ThisA. r. rufulus individual was photographed inKanha Tiger Reserve, in the Indian state ofMadhya Pradesh.
ThePeacock flounder (Bothus mancus) is a species oflefteye flounder found widely in relatively shallow waters in theIndo-Pacific. Thisphotomontage shows four separate views of the same fish, each several minutes apart, starting from the top left. Over the course of the photos, the fishchanges its colors to match its new surroundings, and then finally (bottom right) buries itself in the sand, leaving only the eyes protruding.
Theeastern grey kangaroo (Macropus giganteus) is amarsupial found in the eastern third of Australia, with a population of several million. The eastern grey kangaroo is the second largest living marsupial and native land mammal in Australia, with adult males weighing around 50 to 66 kg (110 to 146 lb) and females weighing around 17 to 40 kg (37 to 88 lb). Like allkangaroos, it is mainlynocturnal andcrepuscular, and is mostly seen early in the morning, or as the light starts to fade in the evening. In the middle of the day, kangaroos rest in the cover of the woodlands andgraze there. Kangaroos are the only large mammals tohop on two legs as their primary means oflocomotion. Thismultiple exposure photograph shows an eastern grey kangaroo hopping inMount Annan, New South Wales.
Asoybean cyst nematode (Heterodera glycines), together with an egg, as viewed through a low-temperaturescanning electron microscope at 1000x magnification. Thisnematode infects the roots of soybeans, and the female nematode eventually becomes acyst. Infection causes various symptoms that may includechlorosis of the leaves and stems, root necrosis, loss in seed yield and suppression of root and shoot growth.
Theleopard shark (Triakis semifasciata) is a species ofhound shark found along thePacific coast ofNorth America from the U.S. state ofOregon toMazatlán in Mexico. Typically measuring 1.2–1.5 m (3.9–4.9 ft) long, this slender-bodied shark is characterized by black saddle-like markings and large spots over its back.
Bryozoa (also known as thePolyzoa,Ectoprocta or commonly asmoss animals) are aphylum of simple,aquaticinvertebrate animals, nearly all living in sedentarycolonies. Typically about 0.5 millimetres (1⁄64 in) long, they have a special feeding structure called alophophore, a "crown" of tentacles used forfilter feeding. The bryozoans are classified as themarine bryozoans (Stenolaemata),freshwater bryozoans (Phylactolaemata), andmostly-marine bryozoans (Gymnolaemata), a few members of which preferbrackish water. Mostmarine bryozoans live in tropical waters, but a few are found inoceanic trenches and polar waters. 5,869living species of bryozoa 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 fourgenera:Aethozooides,Aethozoon,Franzenella, andMonobryozoon, the latter having a statocyst-like organ with a supposed excretory function. (Full article...)
Bolinus cornutus is a predatoryspecies ofsea snail, a marinegastropodmollusk in thefamilyMuricidae. This species is common along the west coast of Africa, where it prefers moderately shallow waters. The shell of the snail is distinctively large, spiny, and club-shaped, usually pale brown or tan in colour, with an elongated and straightsiphonal canal.
TheCommon Brushtail Possum (Trichosurus vulpecula) is the largestpossum species and is perhaps the most widespreadmammal in Australia. It grows to about 32–58 cm (13–23 in) in length, with an additional 24–40 cm (9–16 in) for itsprehensile tail (seen here hanging below the branch). It is mainly afolivore, but has been known to eat small mammals such as rats. It is common in cities, having adapted well to human habitation.
A femaleCalliope Hummingbird (Stellula calliope), the smallest bird found in Canada and the United States, feeding insects to chicks. Found mostly in western North America (althoughvagrants have been found in New York and Connecticut), it ismigratory and winters in southwestern Mexico.
Platyhelminthes (from Ancient Greek πλατύ platy'flat' and ἕλμινς helmins'parasitic worm') is aphylum of relatively simplebilaterian,unsegmented, soft-bodiedinvertebrates commonly calledflatworms orflat worms. Beingacoelomates (having nobody cavity), and having no specialisedcirculatory andrespiratoryorgans, they are restricted to having flattened shapes that allowoxygen and nutrients to pass through their bodies bydiffusion. The digestive cavity has only one opening for both ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, thefood can not be processed continuously. (Full article...)
Thecoconut octopus (Amphioctopus marginatus) is a medium-sizedcephalopod found in tropical waters of the western Pacific Ocean. It commonly preys uponshrimp,crabs, andclams, and displays unusual behaviour, including bipedal walking and gathering and usingcoconut shells and seashells for shelter.
Brittle stars,serpent stars, orophiuroids (from Latin ophiurus'brittle star'; from Ancient Greekὄφις (óphis)'serpent' and οὐρά (ourá)'tail'; referring to the serpent-like arms of the brittle star) areechinoderms in the classOphiuroidea, closely related tostarfish. 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...)
Young amphibians generally undergometamorphosis from an aquatic larval form with gills to an air-breathing adult form withlungs. Amphibiansuse their skin as a secondary respiratory interface, and some small terrestrialsalamanders and frogs even lack lungs and rely entirely on their skin. They are superficially similar toreptiles likelizards, but unlike reptiles and otheramniotes, require access to water bodies to breed. With their complex reproductive needs and permeable skins, amphibians are oftenecological indicators to habitat conditions; in recent decades there has been a dramaticdecline in amphibian populations for many species around the globe. (Full article...)
...thatCaecillians, an order ofamphibians resembling snakes or worms, possess a pair of tentacles, located between their eyes and nostrils which are probably used forolfaction?
Image 5Theblue whale is the largest animal that has ever lived; it can be up to 33.6 metres (110 ft) long. (fromAnimal)
Image 6Apraying mantis indeimatic or threat pose displays conspicuous patches of colour to startle potential predators. This is not warning coloration as the insect is palatable. (fromAnimal coloration)
Image 7The black and yellow warning colours of the cinnabar moth caterpillar,Tyria jacobaeae, are avoided by some birds. (fromAnimal coloration)
Image 10Idealisednephrozoan body plan. With an elongated body and a direction of movement the animal has head and tail ends. Sense organs and mouth form thebasis of the head. Opposed circular and longitudinal muscles enableperistaltic motion. (fromAnimal)
Image 20A clade representation of seven dog breeds in relation to wolves. (fromZoology)
Image 21Animals are unique in having the ball of cells of the earlyembryo (1) develop into a hollow ball orblastula (2). (fromAnimal)
Image 22The microscopic cave snailZospeum tholussum, found at depths of 743 to 1,392 m (2,438 to 4,567 ft) in theLukina Jama–Trojama cave system ofCroatia, is completely blind with a translucent shell (fromFauna)
Image 23Simplified schematic of an island's fauna – all its animal species, highlighted in boxes (fromFauna)
Image 30Animal anatomical engraving fromHandbuch der Anatomie der Tiere für Künstler. (fromZoology)
Image 31A brilliantly-colouredoriental sweetlips fish (Plectorhinchus vittatus) waits while two boldly-patternedcleaner 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 thecleaner fish signal their availability forcleaning service, rather than as prey (fromAnimal coloration)
Image 32Non-bilaterians include sponges (centre) and corals (background). (fromAnimal)
Image 40The bilaterian gut develops in two ways. In manyprotostomes, the blastopore develops into the mouth, while indeuterostomes it becomes the anus. (fromAnimal)
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 thetaxonomic 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 ofDNA barcoding to taxonomy further complicates this; a 2016 barcoding analysis estimated a total count of nearly 100,000insect species forCanada 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.
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