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
Binomial nomenclature called binominal nomenclature or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomen, binominal name or a scientific name; the first part of the name – the generic name – identifies the genus to which the species belongs, while the second part – the specific name or specific epithet – identifies the species within the genus. For example, humans belong within this genus to the species Homo sapiens. Tyrannosaurus rex is the most known binomial; the formal introduction of this system of naming species is credited to Carl Linnaeus beginning with his work Species Plantarum in 1753. But Gaspard Bauhin, in as early as 1623, had introduced in his book Pinax theatri botanici many names of genera that were adopted by Linnaeus; the application of binomial nomenclature is now governed by various internationally agreed codes of rules, of which the two most important are the International Code of Zoological Nomenclature for animals and the International Code of Nomenclature for algae and plants.
Although the general principles underlying binomial nomenclature are common to these two codes, there are some differences, both in the terminology they use and in their precise rules. In modern usage, the first letter of the first part of the name, the genus, is always capitalized in writing, while that of the second part is not when derived from a proper noun such as the name of a person or place. Both parts are italicized when a binomial name occurs in normal text, thus the binomial name of the annual phlox is now written as Phlox drummondii. In scientific works, the authority for a binomial name is given, at least when it is first mentioned, the date of publication may be specified. In zoology "Patella vulgata Linnaeus, 1758"; the name "Linnaeus" tells the reader who it was that first published a description and name for this species of limpet. "Passer domesticus". The original name given by Linnaeus was Fringilla domestica; the ICZN does not require that the name of the person who changed the genus be given, nor the date on which the change was made, although nomenclatorial catalogs include such information.
In botany "Amaranthus retroflexus L." – "L." is the standard abbreviation used in botany for "Linnaeus". "Hyacinthoides italica Rothm. – Linnaeus first named this bluebell species Scilla italica. The name is composed of two word-forming elements: "bi", a Latin prefix for two, "-nomial", relating to a term or terms; the word "binomium" was used in Medieval Latin to mean a two-term expression in mathematics. Prior to the adoption of the modern binomial system of naming species, a scientific name consisted of a generic name combined with a specific name, from one to several words long. Together they formed a system of polynomial nomenclature; these names had two separate functions. First, to designate or label the species, second, to be a diagnosis or description. In a simple genus, containing only two species, it was easy to tell them apart with a one-word genus and a one-word specific name; such "polynomial names" may sometimes look like binomials, but are different. For example, Gerard's herbal describes various kinds of spiderwort: "The first is called Phalangium ramosum, Branched Spiderwort.
The other... is aptly termed Phalangium Ephemerum Virginianum, Soon-Fading Spiderwort of Virginia". The Latin phrases are short descriptions, rather than identifying labels; the Bauhins, in particular Caspar Bauhin, took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words. The adoption by biologists of a system of binomial nomenclature is due to Swedish botanist and physician Carl von Linné, more known by his Latinized name Carl Linnaeus, it was in his 1753 Species Plantarum that he first began using a one-word "trivial name" together with a generic name in a system of binomial nomenclature. This trivial name is what is now known as specific name; the Bauhins' genus names were retained in many of these, but the descriptive part was reduced to a single word. Linnaeus's trivial names introduced an important new idea, namely that the function of a name could be to give a species a unique label; this meant. Thus Gerard's Phalangium ephemerum virginianum became Tradescantia virgi
The danionins are a group of small minnow-type fish belonging to the family Cyprinidae. Members of this group are in the genera Danio and Rasbora, they are native to the fresh waters of South and Southeast Asia, with fewer species in Africa. Many species are available as aquarium fish worldwide. Danio species tend to have horizontal stripes, rows of spots, or vertical bars, have long barbels. Devario species tend to have vertical or horizontal bars, short rudimentary barbels, if barbels are present at all. All danionins are egg scatterers and breed in the rainy season in the wild, they are carnivores living on small crustaceans. The grouping of fish now deemed danionins has been the subject of constant research and speculation throughout the 20th century. Nearly all the fish classed within the genera Danio and Devario were placed in the genus Danio upon discovery. However, in the first part of the 20th century, George S. Myers split them into three genera, Danio and Daniops; the sole species within Myers' Daniops, D. myersi, has long ago been found to be a synonym of Devario laoensis, but his genus Brachydanio lasted for much longer, as it included most of the fish now classed as Danio, whereas Danio included most of the fish now classed as Devario.
However, Danio dangila and Danio feegradei, both of which had most of the characteristics of the Brachydanio were placed within Danios.. In 1941, H. M. Smith attempted to unite all the Brachydanios and Danios species into one genus on the basis of a fish from Thailand, supposed to bridge the gap, he downgraded both Danio and Brachydanio into subgenera and erected a new subgenus of Allodanio with one member, Allodanio ponticulus, but Myers pointed out that A. ponticulus was a member of the genus Barilius. The danionin group was thought to include Parabarilius, Danio and Danionella. In this scheme, danionins were distinguished from other cyprinids by the uniquely shared character of the "danionin notch", a large and peculiarly shaped indentation in the medial margin of the mandibles. However, all of these categories at that time were informal. Microrasbora was not considered to be a part of the danionins, nor closely related to Danionella, a part of the danionins as understood at that time. In the late 1980s and 1990s, doubts grew about the validity of Brachydanio, with species being referred to their original naming of Danio, Fang Fang determined that the genus Danio, recognized up to that point, was paraphyletic.
Fang restricted Danio to the species in the "D. dangila species group", which at the time comprised nine species including D. dangila, D. rerio, D. nigrofasciatus, D. albolineatus. The only Danio species to have been called Danio were D. dangila and D. feegradei. As D. dangila was the first discovered Danio the name Danio had to remain with D. dangila, why the vast majority of species were moved to Devario. The sister group to Devario was deemed to be a clade formed by Inlecypris and Chela, more controversially, Esomus was found to be the sister group of Danio; the relationships of Sundadanio and Microrasbora remained unresolved. The danionin notch was found to not supported to be a danionin synapomorphy. In another paper, Celestichthys margaritatus was described as a new species of the Danioninae, it is most related to Microrasbora erythromicron. The genus is identified as a danionin due specializations of its lower jaw and its numerous anal fin rays. Though it lacks a danionin notch, Celestichthys exhibits the "danionin mandibular knob", a bony process on the side of the mandible behind the danionin notch or where the notch should be.
This knob is better developed in males than females. The fish of Rasborinae invariably have anal fins with three spines and five rays. Celestichthys has 8-10 anal fin rays. Rasborins have the generalized cyprinid principal caudal fin ray count of 10/9, while all Asian cyprinids with fewer than 10/9 principal caudal fin rays are all diminutive species of Danioninae, including Celestichthys, M. erythromicron and Paedocypris. In 2007, an analysis of the phylogenetic relationships of the described genus Paedocypris was published, placing it as the sister taxon to Sundadanio; the clade formed by these two genera was found to be sister to a clade including many danionin genera, as well as some rasborin genera such as Rasbora and Boraras, making the danionin group paraphyletic without these rasborin genera based on these results. This paper considered the danionin genera to be within a larger Rasborinae. In 2007, another study analyzed the relationships of Danio; these authors considered Rasborinae to have priority over Danioninae, suggesting that they have the same meaning.
Danio was found to be the sister group of a clade including Chela, Microrasbora and Inlecypris, rather than in a clade with either Devario or Esomus as in previous studies. This paper supported the close relationship of "Microrasbora" erythromicron to Danio species.
Devario is a genus of fish in the family Cyprinidae native to the rivers and streams of South and Southeast Asia. These fishes have many species having vertical or horizontal stripes; these species consume various small, aquatic insects and worms, as well as, in the case of fry, plankton. 43 species in this genus are recognized
Cypriniformes is an order of ray-finned fish, including the carps, minnows and relatives. This order contains 11-12 families, over 400 genera, more than 4,250 species, with new species being described every few months or so, new genera being recognized frequently, they are most diverse in southeastern Asia, are absent from Australia and South America. Their closest living relatives are the Gymnotiformes and the Siluriformes. Like other orders of the Ostariophysi, fishes of cypriniformes possess a Weberian apparatus, they differ from most of their relatives in having only a dorsal fin on their back. Further differences are the Cypriniformes' unique kinethmoid, a small median bone in the snout, the lack of teeth in the mouth. Instead, they have convergent structures called pharyngeal teeth in the throat. While other groups of fish, such as cichlids possess pharyngeal teeth, the cypriniformes' teeth grind against a chewing pad on the base of the skull, instead of an upper pharyngeal jaw; the most notable family placed here is Cyprinidae.
This is one of the largest families of fish, is distributed across Africa and North America. Most species are freshwater inhabitants, but a considerable number are found in brackish water, such as roach and bream. At least one species is found in the Pacific redfin, Tribolodon brandtii. Brackish water and marine cyprinids are invariably anadromous, swimming upstream into rivers to spawn. Sometimes separated as family Psilorhynchidae, they seem to be specially-adapted fishes of Cyprinidae. Balitoridae and Gyrinocheilidae are families of mountain stream fishes feeding on algae and small invertebrates, they are found only in subtropical Asia. While the former are a speciose group, the latter contain only a handful of species; the suckers are found in temperate North eastern Asia. These large fishes are similar to carps in ecology. Members of Cobitidae common across Eurasia and parts of North Africa. A mid-sized group like the suckers, they are rather similar to catfish in appearance and behaviour, feeding off the substrate and equipped with barbels to help them locate food at night or in murky conditions.
Fishes in the families Cobitidae, Balitoridae and Gyrinocheilidae are called loaches, although it seems that the last do not belong to the lineage of "true" loaches but are related to the suckers. These included all the forms now placed in the superorder Ostariophysi except the catfish, which were placed in the order Siluriformes. By this definition, the Cypriniformes were paraphyletic, so the orders Gonorhynchiformes and Gymnotiformes have been separated out to form their own monophyletic orders; the families of Cypriniformes are traditionally divided into two superfamilies. Superfamily Cyprinioidea contains the carps and minnows and the mountain carps as the family Psilorhynchidae. In 2012 Maurice Kottelat reviewed the superfamily Cobitoidei and under his revision it now consists of the following families: hillstream loaches, Botiidae, true loaches, Gastromyzontidae, sucking loaches, stone loaches, Serpenticobitidae and long-finned loaches. Catostomoidea is treated as a junior synonym of Cobitoidei.
But it seems that it could be split off the Catostomidae and Gyrinocheilidae in a distinct superfamily. While the Cyprinioidea seem more "primitive" than the loach-like forms, they were successful enough never to shift from the original ecological niche of the basal Ostariophysi. Yet, from the ecomorphologically conservative main lineage at least two major radiations branched off; these diversified from the lowlands into torrential river habitats, acquiring similar habitus and adaptations in the process. The mountain carps are apomorphic Cyprinidae close to true carps, or maybe to the danionins. While some details about the phylogenetic structures of this massively diverse family are known – e.g. that Cultrinae and Leuciscinae are rather close relatives and stand apart from Cyprininae – there is no good consensus yet on how the main lineages are interrelated. A systematic list, from the most ancient to the most modern lineages, can thus be given as: Superfamily Cyprinoidei Family Cyprinidae Bonaparte, 1840 and minnows incl.
Psilorhynchidae) Superfamily Cobitoidei Superfamily Catostomoidea Family Catostomidae Agassiz 1850 Superfamily Gyrinocheiloidea Family Gyrinocheilidae Gill 1905 Superfamily Cobitoidea Family Barbuccidae Kottelat 2012 Family Serpenticobitidae Kottelat 2012 Family Botiidae Berg 1940 Family Vaillantellidae Nalbant & Bănărescu 1977 Family Cobitidae Swainson 1838 Family Balitoridae Swainson 1839 Family Gastromyzontidae Fowler 1905 Family Ellopostomatidae Bohlen & Šlechtová 2009 Family Nemacheilidae Regan 1911 Phylogeny based on the work of the following works Cypriniformes include the most primitive of the Ostariophysi in the narrow sense. This is evidenced n
The annelids known as the ringed worms or segmented worms, are a large phylum, with over 22,000 extant species including ragworms and leeches. The species exist in and have adapted to various ecologies – some in marine environments as distinct as tidal zones and hydrothermal vents, others in fresh water, yet others in moist terrestrial environments; the annelids are bilaterally symmetrical, coelomate, invertebrate organisms. They have parapodia for locomotion. Most textbooks still use the traditional division into polychaetes and leech-like species. Cladistic research since 1997 has radically changed this scheme, viewing leeches as a sub-group of oligochaetes and oligochaetes as a sub-group of polychaetes. In addition, the Pogonophora and Sipuncula regarded as separate phyla, are now regarded as sub-groups of polychaetes. Annelids are considered members of the Lophotrochozoa, a "super-phylum" of protostomes that includes molluscs, brachiopods and nemerteans; the basic annelid form consists of multiple segments.
Each segment has the same sets of organs and, in most polychates, has a pair of parapodia that many species use for locomotion. Septa separate the segments of many species, but are poorly defined or absent in others, Echiura and Sipuncula show no obvious signs of segmentation. In species with well-developed septa, the blood circulates within blood vessels, the vessels in segments near the front ends of these species are built up with muscles that act as hearts; the septa of such species enable them to change the shapes of individual segments, which facilitates movement by peristalsis or by undulations that improve the effectiveness of the parapodia. In species with incomplete septa or none, the blood circulates through the main body cavity without any kind of pump, there is a wide range of locomotory techniques – some burrowing species turn their pharynges inside out to drag themselves through the sediment. Earthworms are oligochaetes that support terrestrial food chains both as prey and in some regions are important in aeration and enriching of soil.
The burrowing of marine polychaetes, which may constitute up to a third of all species in near-shore environments, encourages the development of ecosystems by enabling water and oxygen to penetrate the sea floor. In addition to improving soil fertility, annelids serve humans as bait. Scientists observe annelids to monitor the quality of fresh water. Although blood-letting is used less by doctors, some leech species are regarded as endangered species because they have been over-harvested for this purpose in the last few centuries. Ragworms' jaws are now being studied by engineers as they offer an exceptional combination of lightness and strength. Since annelids are soft-bodied, their fossils are rare – jaws and the mineralized tubes that some of the species secreted. Although some late Ediacaran fossils may represent annelids, the oldest known fossil, identified with confidence comes from about 518 million years ago in the early Cambrian period. Fossils of most modern mobile polychaete groups appeared by the end of the Carboniferous, about 299 million years ago.
Palaeontologists disagree about whether some body fossils from the mid Ordovician, about 472 to 461 million years ago, are the remains of oligochaetes, the earliest indisputable fossils of the group appear in the Tertiary period, which began 66 million years ago. There are over 22,000 living annelid species, ranging in size from microscopic to the Australian giant Gippsland earthworm and Amynthas mekongianus, which can both grow up to 3 metres long. Although research since 1997 has radically changed scientists' views about the evolutionary family tree of the annelids, most textbooks use the traditional classification into the following sub-groups: Polychaetes; as their name suggests, they have multiple chetae per segment. Polychaetes have parapodia that function as limbs, nuchal organs that are thought to be chemosensors. Most are marine animals, although a few species live in fresh water and fewer on land. Clitellates; these have few or no chetae per segment, no nuchal organs or parapodia. However, they have a unique reproductive organ, the ring-shaped clitellum around their bodies, which produces a cocoon that stores and nourishes fertilized eggs until they hatch or, in moniligastrids, yolky eggs that provide nutrition for the embyros.
The clitellates are sub-divided into: Oligochaetes. Oligochaetes have a sticky pad in the roof of the mouth. Most are burrowers that feed on wholly or decomposed organic materials. Hirudinea, whose name means "leech-shaped" and whose best known members are leeches. Marine species are blood-sucking parasites on fish, while most freshwater species are predators, they have suckers at both ends of their bodies, use these to move rather like inchworms. The Archiannelida, minute annelids that live in the spaces between grains of marine sediment, were treated as a separate class because of their simple body structure, but are now regarded as polychaetes; some other groups of animals have been classified in various ways, but are now regarded as annelids: Pogonophora / Siboglinidae were first discovered in 1914, their lack of a recognizable gut made it difficult to classify them. They have been classified as a separate phylum, Pogonophora, or as two phyla and Vestimentifera. More they have been re-classified as a family, Siboglinidae
International Union for Conservation of Nature
The International Union for Conservation of Nature is an international organization working in the field of nature conservation and sustainable use of natural resources. It is involved in data gathering and analysis, field projects and education. IUCN's mission is to "influence and assist societies throughout the world to conserve nature and to ensure that any use of natural resources is equitable and ecologically sustainable". Over the past decades, IUCN has widened its focus beyond conservation ecology and now incorporates issues related to sustainable development in its projects. Unlike many other international environmental organisations, IUCN does not itself aim to mobilize the public in support of nature conservation, it tries to influence the actions of governments and other stakeholders by providing information and advice, through building partnerships. The organization is best known to the wider public for compiling and publishing the IUCN Red List of Threatened Species, which assesses the conservation status of species worldwide.
IUCN has a membership of over 1400 non-governmental organizations. Some 16,000 scientists and experts participate in the work of IUCN commissions on a voluntary basis, it employs 1000 full-time staff in more than 50 countries. Its headquarters are in Switzerland. IUCN has observer and consultative status at the United Nations, plays a role in the implementation of several international conventions on nature conservation and biodiversity, it was involved in establishing the World Wide Fund for Nature and the World Conservation Monitoring Centre. In the past, IUCN has been criticized for placing the interests of nature over those of indigenous peoples. In recent years, its closer relations with the business sector have caused controversy. IUCN was established in 1948, it was called the International Union for the Protection of Nature and the World Conservation Union. Establishment IUCN was established on 5 October 1948, in Fontainebleau, when representatives of governments and conservation organizations signed a formal act constituting the International Union for the Protection of Nature.
The initiative to set up the new organisation came from UNESCO and from its first Director General, the British biologist Julian Huxley. The objectives of the new Union were to encourage international cooperation in the protection of nature, to promote national and international action and to compile and distribute information. At the time of its founding IUPN was the only international organisation focusing on the entire spectrum of nature conservation Early years: 1948–1956 IUPN started out with 65 members, its secretariat was located in Brussels. Its first work program focused on saving species and habitats and applying knowledge, advancing education, promoting international agreements and promoting conservation. Providing a solid scientific base for conservation action was the heart of all activities. IUPN and UNESCO were associated, they jointly organized the 1949 Conference on Protection of Nature. In preparation for this conference a list of gravely endangered species was drawn up for the first time, a precursor of the IUCN Red List of Threatened Species.
In the early years of its existence IUCN depended entirely on UNESCO funding and was forced to temporarily scale down activities when this ended unexpectedly in 1954. IUPN was successful in engaging prominent scientists and identifying important issues such as the harmful effects of pesticides on wildlife but not many of the ideas it developed were turned into action; this was caused by unwillingness to act on the part of governments, uncertainty about the IUPN mandate and lack of resources. In 1956, IUPN changed its name to International Union for Conservation of Nature and Natural Resources. Increased profile and recognition: 1956–1965 In the 1950s and 1960s Europe entered a period of economic growth and formal colonies became independent. Both developments had impact on the work of IUCN. Through the voluntary involvement of experts in its Commissions IUCN was able to get a lot of work done while still operating on a low budget, it established links with the Council of Europe. In 1961, at the request of United Nations Economic and Social Council, the United Nations Economic and Social Council, IUCN published the first global list of national parks and protected areas which it has updated since.
IUCN's best known publication, the Red Data Book on the conservation status of species, was first published in 1964. IUCN began to play a part in the development of international treaties and conventions, starting with the African Convention on the Conservation of Nature and Natural Resources. Environmental law and policy making became a new area of expertise. Africa was the focus of many of the early IUCN conservation field projects. IUCN supported the ‘Yellowstone model’ of protected area management, which restricted human presence and activity in order to protect nature. IUCN and other conservation organisations were criticized for protecting nature against people rather than with people; this model was also applied in Africa and played a role in the decision to remove the Maasai people from Serengeti National Park and the Ngorongoro Conservation Area. To establish a stable financial basis for its work, IUCN participated in setting up the World Wildlife Fund