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...)
In spite of common urban legends and misconceptions labeling the eastern green mamba an aggressive, fast-moving “people-chaser”, it is in fact a shy and elusive species that remains hidden in the trees, and is rarely seen. This seclusion is usually attributed to its arboreal habitat and green colouration, which acts as effective camouflage in its natural environment. Even with its deadly venom, the green mamba has to protect itself from predators, including birds of prey and other snakes, such as cobras. It has been observed engaging in ambush predation, a trait seen among many Viperidae species, contrary to the active hunting style typical of other Elapidae snakes. It preys on arboreal and winged animals, such as birds and their chicks and eggs, bats, and arboreal rodents such as mice, rats, and gerbils. (Full article...)
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.
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.
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.
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.
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.
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...)
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 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.
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 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.
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 eastern grey kangaroo (Macropus giganteus) is a marsupial 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 all kangaroos, it is mainly nocturnal and crepuscular, 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 and graze there. Kangaroos are the only large mammals to hop on two legs as their primary means of locomotion. This multiple exposure photograph shows an eastern grey kangaroo hopping in Mount Annan, New South Wales.
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 waterangelfish, 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.
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 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...)
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.
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 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...)
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Bharattherium is a mammal that lived in India during the Maastrichtian (latest Cretaceous) and possibly the Paleocene. The genus has a single species, Bharattherium bonapartei. It is part of the gondwanathere family Sudamericidae, which is also found in Madagascar and South America during the latest Cretaceous. The first fossil of Bharattherium was discovered in 1989 and published in 1997, but the animal was not named until 2007, when two teams independently named the animal Bharattherium bonapartei and Dakshina jederi. The latter name is now a synonym. Bharattherium is known from a total of eight isolated fossil teeth, including one incisor and seven molariforms (molar-like teeth, either premolars or true molars).
Bharattherium molariforms are high, curved teeth, with a height of 6 to 8.5 millimetres (0.24 to 0.33 in). In a number of teeth tentatively identified as fourth lower molariforms (mf4), there is a large furrow on one side and a deep cavity (infundibulum) in the middle of the tooth. Another tooth, perhaps a third lower molariform, has two furrows on one side and three infundibula on the other. The tooth enamel has traits that have been interpreted as protecting against cracks in the teeth. The hypsodont (high-crowned) teeth of sudamericids like Bharattherium are reminiscent of later grazing mammals, and the discovery of grass in Indian fossil sites contemporaneous with those yielding Bharattherium suggest that sudamericids were indeed grazers. (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"?
Image 21Idealised 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 22A 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 23A 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 24Squid chromatophores appear as black, brown, reddish and pink areas in this micrograph. (from Animal coloration)
Image 25Linnaeus's table of the animal kingdom from the first edition of Systema Naturae (1735) (from Zoology)
Image 26The 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 42Kelp gull chicks peck at red spot on mother's beak to stimulate the regurgitating reflex. (from Zoology)
Image 43The 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 44Fish and frog melanophores are cells that can change colour by dispersing or aggregating pigment-containing bodies. (from Animal coloration)
Image 45This frog changes its skin colour to control its temperature. (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.
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