Hawks are a group of medium-sized diurnal birds of prey of the family Accipitridae. Hawks are distributed and vary in size; the subfamily Accipitrinae includes goshawks, sharp-shinned hawks and others. This subfamily are woodland birds with long tails and high visual acuity, they hunt by dashing from a concealed perch. In the Americas, members of the Buteo group are called hawks. Buteos have broad wings and sturdy builds, they are larger-winged, shorter-tailed and fly further distances in open areas than accipiters. Buteos pounce on their prey rather than hunting in a fast horizontal pursuit; the terms accipitrine hawk and buteonine hawk are used to distinguish between the types in regions where hawk applies to both. The term "true hawk" is sometimes used for the accipitrine hawks in regions where buzzard is preferred for the buteonine hawks. All these groups are members of the Accipitridae family, which includes the hawks and buzzards as well as kites and eagles; some authors use "hawk" for any small to medium Accipitrid, not an eagle.
The common names of some birds include the term "hawk", reflecting traditional usage rather than taxonomy. For example, some people may call an osprey a "fish hawk" or a peregrine falcon a "duck hawk". Falconry was once called "hawking" and any bird used for falconry could be referred to as a hawk. Aristotle listed eleven types of ἱέρακες: aisalōn, hypotriorchēs, leios, phassophonos, pternis and triorchēs. Pliny numbered sixteen kinds of hawks, but named only aigithos, kenchrēïs, triorchēs; the accipitrine hawks hunt birds as their primary prey. They are called "hen-hawks", or "wood-hawks" because of their woodland habitat; the subfamily Accipitrinae contains Accipiter. Melierax may be given a subfamily of its own. Erythrotriorchis is traditionally included in Accipitrinae, but is a convergent genus from an unrelated group; the "Buteo group" includes genera Buteo, Parabuteo and most of Leucopternis. Members of this group have been called "hawk-buzzards". Proposed new genera Morphnarchus and Pseudastur are formed from members of Buteo and Leucopternis.
The "Buteogallus group" are called hawks, with the exception of the solitary eagles. Buteo is the type genus of the subfamily Buteoninae. Traditionally this subfamily includes eagles and sea-eagles. Lerner and Mindell proposed placing those into separate subfamilies, leaving only the buteonine hawks/buzzards in Buteoninae. In February 2005, Canadian ornithologist Louis Lefebvre announced a method of measuring avian "IQ" by measuring their innovation in feeding habits. Based on this scale, hawks were named among the most intelligent birds. Hawks have four types of colour receptors in the eye; these give hawks the ability to perceive not only the visible range but the ultraviolet part of the spectrum. Other adaptations allow for the detection of polarised magnetic fields; this is due to the large number of photoreceptors in the retina, a high number of nerves connecting these receptors to the brain, an indented fovea, which magnifies the central portion of the visual field. Hawks are known to be able hunters.
The female is larger than the male. Like most birds, the hawk migrates in the spring. Different types of hawks choose separate times in each season to migrate; the autumn migrating season ends mid-December. It has been studied; the long-distance travelers tend to begin in early autumn while the short distance travelers start much later. Thus, the longer the distance the earlier the bird begins its journey. There have been studies on the speed and efficiency of the bird's migration that show that it is better for a hawk to arrive at its destination as early as possible; this is because the first bird that arrives has the first pick of mates, living area and survival necessities. The more fat a bird has when it starts its migration, the better chance it has of making the trip safely. Kerlinger states that studies have shown that a bird has more body fat when it begins its migration, before it leaves, than when has arrived at its destination. One of the most important parts of the hawk's migration is the flight direction because the direction or path the bird chooses to take could affect its migration.
The force of wind is a variable because it could either throw the bird off course or push it in the right direction, depending on the direction of the wind. To ensure a safer journey, a hawk tries to avoid any large bodies of water in the spring and fall by detouring around a lake or flying along a border. Hawkwatching is a citizen scientist activity that monitors hawk migration and provides data to the scientific community; the red-tailed hawk is the most common hawk in North America. Past observations have indicated that while hawks can adapt to any surrounding, hawks prefer a habitat, open. Hawks like to live in places like deserts and fields as it is easier to find prey; as they are able to live anywhere, they can be found in mountainous plains and tropical, moist areas. Hawks have been found in places such as Centra
Iguania is an infraorder of squamate reptiles that includes iguanas, chameleons and New World lizards like anoles and phrynosomatids. Using morphological features as a guide to evolutionary relationships, the Iguania are believed to form the sister group to the remainder of the Squamata. However, molecular information has placed Iguania well within the Squamata as sister taxa to the Anguimorpha and related to snakes. Iguanians are arboreal and have primitive fleshy, non-prehensile tongues, although the tongue is modified in chameleons; the group has a fossil record. The Iguania include these extant families: Clade Acrodonta Family Agamidae – agamid lizards, Old World arboreal lizards Family Chamaeleonidae – chameleons Clade Pleurodonta – American arboreal lizards, iguanas Family Leiocephalidae Genus Leiocephalus: curly-tailed lizards Family Corytophanidae – helmet lizards Family Crotaphytidae – collared lizards, leopard lizards Family Hoplocercidae – dwarf and spinytail iguanas Family Iguanidae – marine, Galapagos land, rock, desert and chuckwalla iguanas Family Tropiduridae – tropidurine lizards subclade of Tropiduridae Tropidurini – neotropical ground lizards Family Dactyloidae – anoles Family Polychrotidae subclade of Polychrotidae Polychrus Family Phrynosomatidae – North American spiny lizards Family Liolaemidae – South American swifts Family Opluridae – Malagasy iguanas Family Leiosauridae – leiosaurs subclade of Leiosaurini Leiosaurae subclade of Leiosaurini Anisolepae Below is a cladogram from the phylogenetic analysis of Daza et al. showing the interrelationships of extinct and living iguanians
A raven is one of several larger-bodied species of the genus Corvus. These species do not form a single taxonomic group within the genus. There is no consistent distinction between "crows" and "ravens", these appellations have been assigned to different species chiefly on the basis of their size, crows being smaller than ravens; the largest raven species are the thick-billed raven. The term "raven" referred to the common raven, the type species of the genus Corvus, which has a larger distribution than any other species of Corvus, ranging over much of the Northern Hemisphere; the modern English word raven has cognates in all other Germanic languages, including Old Norse hrafn and Old High German raban, all of which descend from Proto-Germanic *hrabanaz. Collective nouns for a group of ravens include "unkindness", "treachery", "conspiracy". In practice, most people use the more generic "flock". Corvus albicollis – white-necked raven Corvus corax – common raven Corvus coronoides – Australian raven Corvus crassirostris – thick-billed raven Corvus cryptoleucus – Chihuahuan raven Corvus mellori – little raven Corvus rhipidurus – fan-tailed raven Corvus ruficollis – brown-necked raven Corvus tasmanicus – forest raven †Corvus moriorum – Chatham raven †Corvus antipodum – New Zealand raven †Corvus corax varius morpha leucophaeus – pied raven Cultural depictions of ravens Ravens of the Tower of London Raven videos on the Internet Bird Collection North American ravens on eNature
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results
Wikispecies is a wiki-based online project supported by the Wikimedia Foundation. Its aim is to create a comprehensive free content catalogue of all species. Jimmy Wales stated that editors are not required to fax in their degrees, but that submissions will have to pass muster with a technical audience. Wikispecies is available under the GNU Free Documentation License and CC BY-SA 3.0. Started in September 2004, with biologists across the world invited to contribute, the project had grown a framework encompassing the Linnaean taxonomy with links to Wikipedia articles on individual species by April 2005. Benedikt Mandl co-ordinated the efforts of several people who are interested in getting involved with the project and contacted potential supporters in early summer 2004. Databases were evaluated and the administrators contacted, some of them have agreed on providing their data for Wikispecies. Mandl defined two major tasks: Figure out how the contents of the data base would need to be presented—by asking experts, potential non-professional users and comparing that with existing databases Figure out how to do the software, which hardware is required and how to cover the costs—by asking experts, looking for fellow volunteers and potential sponsorsAdvantages and disadvantages were discussed by the wikimedia-I mailing list.
The board of directors of the Wikimedia Foundation voted by 4 to 0 in favor of the establishment of a Wikispecies. The project is hosted at species.wikimedia.org. It was merged to a sister project of Wikimedia Foundation on September 14, 2004. On October 10, 2006, the project exceeded 75,000 articles. On May 20, 2007, the project exceeded 100,000 articles with a total of 5,495 registered users. On September 8, 2008, the project exceeded 150,000 articles with a total of 9,224 registered users. On October 23, 2011, the project reached 300,000 articles. On June 16, 2014, the project reached 400,000 articles. On January 7, 2017, the project reached 500,000 articles. On October 30, 2018, the project reached 600,000 articles, a total of 1.12 million pages. Wikispecies comprises taxon pages, additionally pages about synonyms, taxon authorities, taxonomical publications, institutions or repositories holding type specimen. Wikispecies asks users to use images from Wikimedia Commons. Wikispecies does not allow the use of content.
All Species Foundation Catalogue of Life Encyclopedia of Life Tree of Life Web Project List of online encyclopedias The Plant List Wikispecies, The free species directory that anyone can edit Species Community Portal The Wikispecies Charter, written by Wales
Reptiles are tetrapod animals in the class Reptilia, comprising today's turtles, snakes, lizards and their extinct relatives. The study of these traditional reptile orders combined with that of modern amphibians, is called herpetology; because some reptiles are more related to birds than they are to other reptiles, the traditional groups of "reptiles" listed above do not together constitute a monophyletic grouping or clade. For this reason, many modern scientists prefer to consider the birds part of Reptilia as well, thereby making Reptilia a monophyletic class, including all living Diapsids; the earliest known proto-reptiles originated around 312 million years ago during the Carboniferous period, having evolved from advanced reptiliomorph tetrapods that became adapted to life on dry land. Some early examples include Casineria. In addition to the living reptiles, there are many diverse groups that are now extinct, in some cases due to mass extinction events. In particular, the Cretaceous–Paleogene extinction event wiped out the pterosaurs, plesiosaurs and sauropods, as well as many species of theropods, including troodontids, dromaeosaurids and abelisaurids, along with many Crocodyliformes, squamates.
Modern non-avian reptiles inhabit all the continents except Antarctica, although some birds are found on the periphery of Antarctica. Several living subgroups are recognized: Testudines, 350 species. Reptiles are tetrapod vertebrates, creatures that either have four limbs or, like snakes, are descended from four-limbed ancestors. Unlike amphibians, reptiles do not have an aquatic larval stage. Most reptiles are oviparous, although several species of squamates are viviparous, as were some extinct aquatic clades – the fetus develops within the mother, contained in a placenta rather than an eggshell; as amniotes, reptile eggs are surrounded by membranes for protection and transport, which adapt them to reproduction on dry land. Many of the viviparous species feed their fetuses through various forms of placenta analogous to those of mammals, with some providing initial care for their hatchlings. Extant reptiles range in size from a tiny gecko, Sphaerodactylus ariasae, which can grow up to 17 mm to the saltwater crocodile, Crocodylus porosus, which can reach 6 m in length and weigh over 1,000 kg.
In the 13th century the category of reptile was recognized in Europe as consisting of a miscellany of egg-laying creatures, including "snakes, various fantastic monsters, assorted amphibians, worms", as recorded by Vincent of Beauvais in his Mirror of Nature. In the 18th century, the reptiles were, from the outset of classification, grouped with the amphibians. Linnaeus, working from species-poor Sweden, where the common adder and grass snake are found hunting in water, included all reptiles and amphibians in class "III – Amphibia" in his Systema Naturæ; the terms "reptile" and "amphibian" were interchangeable, "reptile" being preferred by the French. Josephus Nicolaus Laurenti was the first to formally use the term "Reptilia" for an expanded selection of reptiles and amphibians similar to that of Linnaeus. Today, the two groups are still treated under the same heading as herptiles, it was not until the beginning of the 19th century that it became clear that reptiles and amphibians are, in fact, quite different animals, Pierre André Latreille erected the class Batracia for the latter, dividing the tetrapods into the four familiar classes of reptiles, amphibians and mammals.
The British anatomist Thomas Henry Huxley made Latreille's definition popular and, together with Richard Owen, expanded Reptilia to include the various fossil "antediluvian monsters", including dinosaurs and the mammal-like Dicynodon he helped describe. This was not the only possible classification scheme: In the Hunterian lectures delivered at the Royal College of Surgeons in 1863, Huxley grouped the vertebrates into mammals and ichthyoids, he subsequently proposed the names of Ichthyopsida for the latter two groups. In 1866, Haeckel demonstrated that vertebrates could be divided based on their reproductive strategies, that reptiles and mammals were united by the amniotic egg; the terms "Sauropsida" and "Theropsida" were used again in 1916 by E. S. Goodrich to distinguish between lizards and their relatives on the one hand and mammals and their extinct relatives on the other. Goodrich supported this division by the nature of the hearts and blood vessels in each group, other features, such as the structure of the forebrain.
According to Goodrich, both lineages evolved from an earlier stem group, Protosauria in which he included some animals today considered reptile-like amphibians, as well as early reptiles. In 1956, D. M. S. Watson observed that the first two groups diverged early in reptilian history, so he divided Goodrich's Protosauria between them, he reinterpreted Sauropsida and Theropsida to exclude birds and mammals, respectively. Thus his Sauropsida included Procolophonia, Millerosauria, Squamata, Rhynchocephalia