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.
Grasshoppers are a group of insects belonging to the suborderCaelifera. They are amongst what are possibly the most ancient living groups of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago.
Grasshoppers are typically ground-dwelling insects with powerful hind legs which allow them to escape from threats by leaping vigorously. Their front leg is shorter and used for grasping food. As hemimetabolous insects, they do not undergo complete metamorphosis; they hatch from an egg into a nymph or "hopper" which undergoes five moults, becoming more similar to the adult insect at each developmental stage. The grasshopper hears through the tympanal organ which can be found in the first segment of the abdomen attached to the thorax; while its sense of vision is in the compound eyes, the change in light intensity is perceived in the simple eyes (ocelli). At high population densities and under certain environmental conditions, some grasshopper species can change colour and behavior and form swarms. Under these circumstances, they are known as locusts. (Full article...)
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.
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 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.
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 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...)
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.
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...)
The maxima clam (Tridacna maxima) is a species of bivalve found throughout the Indo-Pacific. It is found on the surface of reefs or sand, or partly embedded in coral (as with this specimen), in the oceans surrounding east Africa, India, China, Australia, Southeast Asia and the islands of the Pacific. This clam is much sought after in the aquarium trade, as its often striking coloration—the result of crystalline pigment—mimics that of the true giant clam.
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.
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.
The plains zebra (Equus quagga, subspecies Grant's zebra pictured) is the most common and geographically widespread species of zebra. It ranges from the south of Ethiopia through East Africa to as far south as Angola and eastern South Africa. The plains zebra is mid-sized, smaller on average than the other two zebra species, and thick-bodied with relatively short legs. Adults of both sexes can stand from 1.1 to 1.47 m (3.6 to 4.8 ft) high at the shoulder, are 2 to 2.5 m (6.6 to 8.2 ft) long (excluding the tail), and weigh 175 to 387 kg (386 to 853 lb), with males slightly heavier than females.
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 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.
The leopard shark (Triakis semifasciata) is a species of hound shark found along the Pacific coast of North America from the U.S. state of Oregon to Mazatlán 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.
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Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné, was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming organisms. He is known as the "father of modern taxonomy". Many of his writings were in Latin; his name is rendered in Latin as Carolus Linnæus and, after his 1761 ennoblement, as Carolus a Linné.
Linnaeus was the son of a curate and he was born in Råshult, the countryside of Småland, in southern Sweden. He received most of his higher education at Uppsala University and began giving lectures in botany there in 1730. He lived abroad between 1735 and 1738, where he studied and also published the first edition of his Systema Naturae in the Netherlands. He then returned to Sweden where he became professor of medicine and botany at Uppsala. In the 1740s, he was sent on several journeys through Sweden to find and classify plants and animals. In the 1750s and 1760s, he continued to collect and classify animals, plants, and minerals, while publishing several volumes. By the time of his death in 1778, he was one of the most acclaimed scientists in Europe. (Full article...)
...that Lampreys are called "nine-eyed eels" (i.e., per side) from a counting of their seven external gill slits on a side with one eye and the nostril?
Image 6A 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 8The 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 10The black and yellow warning colours of the cinnabar moth caterpillar, Tyria jacobaeae, are avoided by some birds. (from Animal coloration)
Image 11A 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 25The 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 27Linnaeus's table of the animal kingdom from the first edition of Systema Naturae (1735) (from Zoology)
Image 28Non-bilaterians include sponges (centre) and corals (background). (from Animal)
Image 29A gun dog retrieving a duck during a hunt (from Animal)
Image 30Idealised 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 31The hawk-cuckoo resembles a predatory shikra, giving the cuckoo time to lay eggs in a songbird's nest unnoticed (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.