NationMaster - Encyclopedia: Amphibian

Traditionally, amphibians have included all tetrapods that are not amniotes. They are divided into three subclasses, of which two are only known as extinct subclasses: Prehistoric amphibians are various amphibians that lived before recorded history. ... Groups See text. ... Living subgroups Class Synapsida Class Mammalia (mammals) Class Sauropsida Anapsida Testudines (turtles) Diapsida Lepidosauria Squamata (lizards & snakes) Sphenodontida (tuatara) Archosauria Crocodilia (crocodiles) Class Aves (birds) The amniotes are a taxon of tetrapod vertebrates that include the Synapsida (mammals) and Sauropsida (reptiles and dinosaurs, including birds). ... In biology, a subclass is one level below a class. ...

Of these only the last subclass includes recent species. Labyrinthodont (Greek, maze-toothed) is an obsolete term for any member of an extinct superorder or subclass (Labyrinthodontia) of amphibians, which constituted some of the dominant animals of Late Paleozoic and Early Mesozoic times (about 350 to 210 million years ago). ... Groups Acherontiscidae Adelospondyli Aïstopoda Lysorophia Microsauria Nectridea Lepospondyli are a group of small but diverse Carboniferous to early Permian tetrapods. ... Orders Anura Caudata Gymnophiona The subclass Lissamphibia includes all recent amphibians. ...

With the cladistic revolution, this classification has been modified, or changed, and the Labyrinthodontia discarded as being a paraphyletic group without unique defining features apart from shared primitive characteristics. Classification varies according to the preferred phylogeny of the author, and whether they use a stem-based or node-based classification. Generally amphibians are defined as the group that includes the common ancestors of all living amphibians (frogs, salamanders, etc) and all their descendants. This may also include extinct groups like the temnospondyls (traditionally placed in the disbanded subclass "labyrinthodontia"), and the Lepospondyls. This means that there are a now large number of basal Devonian and Carboniferous tetrapod groups, described as "amphibians" in earlier books, that are no longer placed in the formal Amphibia. Greek clados = branch) or phylogenetic systematics is a branch of biology that determines the evolutionary relationships of living things based on derived similarities. ... Paraphyletic - Wikipedia /**/ @import /skins-1. ... This cladogram shows the relationship among various insect groups. ... In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ... Greek clados = branch) or phylogenetic systematics is a branch of biology that determines the evolutionary relationships of living things based on derived similarities. ... Groups Edopoidea Edopidae Cochleosauridae Euskelia Eryopoidea Eryopidae Zatrachydidae Dissorophoidea Limnarchia Dvinosauria Archegosauridae Stereospondyli Trematosauroidea Capitosauroidea Metoposauroidea Plagiosauroidea Rhytidosteidae Brachyopoidea Brachyopidae Chigutosauridae Temnospondyli are an important and extremely diverse taxon of small to giant labyrinthodont amphibians that flourished worldwide during the Carboniferous, Permian, and Triassic periods. ... In phylogenetics, basal members of a group diverged earlier than a subgroup of others (or vice versa). ... For the Celtic language, see Southwestern Brythonic language; for the residents of the English county, see Devon. ... The Carboniferous is a geologic period and system that extends from the end of the Devonian period, about 359. ... Groups See text. ...

All recent amphibians are included in the subclass Lissamphibia, superorder Salientia, which is usually considered a clade (which means that it is thought that they evolved from a common ancestor apart from other extinct groups), although it has also been suggested also that salamanders arose separately from a temnospondyl-like ancestor (Carroll, 2007). Download high resolution version (1326x864, 236 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (1326x864, 236 KB) Wikipedia does not have an article with this exact name. ... Binomial name Salamandra salamandra (Linnaeus, 1758) The Fire Salamander (Salamandra salamandra) is probably the most well-known salamander species in Europe. ... A clade is a term belonging to the discipline of cladistics. ...

Authorities also disagree on whether Salientia is a Superorder that includes the order Anura, or whether Anura is a sub-order of the order Salientia. Practical considerations seem to favour using the former arrangement now.

The Lissamphibia, superorder Salientia, are traditionally divided into three orders, but an extinct salamander-like family, the Albanerpetontidae, is now considered part of the Lissamphibia, besides the superorder Salientia. Furthermore, Salientia includes all three recent orders plus a single Triassic proto-frog, Triadobatrachus. In scientific classification used in biology, the order (Latin: ordo, plural ordines) is a rank between class and family (termed a taxon at that rank). ... The Triassic is a geologic period that extends from about 251 to 199 Ma (million years ago). ... Triadobatrachus is an extinct genus of frog. ...

The actual number of species partly also depends on the taxonomic classification followed, the two most common classifications being the classification of the website AmphibiaWeb, University of California (Berkeley) and the classification by herpetologist Darrel Frost and The American Museum of Natural History, available as the online reference database Amphibian Species of the World (see external links below). The numbers of species cited above follow Frost. Orders Anura Caudata Gymnophiona The subclass Lissamphibia includes all recent amphibians. ... Distribution of frogs (in black) Suborders Archaeobatrachia Mesobatrachia Neobatrachia - List of Anuran families The frogness babe is an amphibian in the order Anura (meaning tail-less from Greek an-, without + oura, tail), formerly referred to as Salientia (Latin saltare, to jump). ... For other uses, see Toad (disambiguation). ... For other uses, see Salamander (disambiguation). ... This article is about the animal. ... Families Rhinatrematidae Ichthyophiidae Uraeotyphlidae Scolecomorphidae Typhlonectidae Caeciliidae The Caecilians are an order (Gymnophiona or Apoda) of amphibians that superficially resemble earthworms or snakes. ... Herpetology is the branch of zoology concerned with the study of reptiles and amphibians including their classification, ecology, behavior, physiology, anatomy, and paleontology. ...

Systems

Reproductive

For the purpose of reproduction most amphibians are bound to fresh water. A few tolerate brackish water, but there are no true seawater amphibians. Several hundred frog species in adaptive radiations (e.g., Eleutherodactylus, the Pacific Platymantines, the Australo-Papuan microhylids, and many other tropical frogs), however, do not need any water whatsoever. They reproduce via direct development, an ecological and evolutionary adaptation that has allowed them to be completely independent from free-standing water. Almost all of these frogs live in wet tropical rainforests and their eggs hatch directly into miniature versions of the adult, passing through the tadpole stage within the egg. Several species have also adapted to arid and semi-arid environments, but most of them still need water to lay their eggs. Symbiosis with single celled algae that lives in the jelly-like layer of the eggs has evolved several times. The larvae (tadpoles or polliwogs) breathe with exterior gills. After hatching, they start to transform gradually into the adult's appearance. This process is called metamorphosis. Typically, the animals then leave the water and become terrestrial adults, but there are many interesting exceptions to this general way of reproduction. Image File history File links Caecilian. ... Image File history File links Caecilian. ... Families Rhinatrematidae Ichthyophiidae Uraeotyphlidae Scolecomorphidae Typhlonectidae Caeciliidae The Caecilians are an order (Gymnophiona or Apoda) of amphibians that superficially resemble earthworms or snakes. ... San Antonio redirects here. ... Biological reproduction is the biological process by which new individual organisms are produced. ... For the village on the Isle of Wight, see Freshwater, Isle of Wight. ... Brackish redirects here. ... Annual mean sea surface salinity for the World Ocean. ... Species Many, see text. ... This article is about evolution in biology. ... Tropic wet forests in the World Tropical and subtropical moist broadleaf forests, also known as tropical wet forests, are a tropical and subtropical forest biome. ... For other uses, see Tadpole (disambiguation). ... For other uses, see Symbiosis (disambiguation). ... For the programming language, see algae (programming language). ... For other uses, see Gill (disambiguation). ... A cicada in the process of shedding. ...

The most obvious part of the amphibian metamorphosis is the formation of four legs in order to support the body on land. But there are several other changes:

Among quadrupeds, the respiratory system generally includes tubes, such as the bronchi, used to carry air to the lungs, where gas exchange takes place. ... For the village in Tibet, see Lung, Tibet. ... Human submaxillary gland. ... Dehydration (hypohydration) is the removal of water (hydro in ancient Greek) from an object. ... The tympanic membrane, colloquially known as the eardrum, is a thin membrane that separates the external ear from the middle ear. ... For other uses, see Ear (disambiguation). ... A scorpion tail The tail is the section at the rear end of an animals body; in general, the term refers to a distinct, flexible appendage to the torso. ...

Conservation

Dramatic declines in amphibian populations, including population crashes and mass localized extinction, have been noted in the past two decades from locations all over the world, and amphibian declines are thus perceived as one of the most critical threats to global biodiversity. A number of causes are believed to be involved, including habitat destruction and modification, over-exploitation, pollution, introduced species, climate change, destruction of the ozone layer (ultraviolet radiation has shown to be especially damaging to the skin, eyes, and eggs of amphibians), and diseases like chytridiomycosis. However, many of the causes of amphibian declines are still poorly understood, and are a topic of ongoing discussion. A global strategy to stem the crisis has been released in the form of the Amphibian Conservation Action Plan (available at www.amphibians.org). Developed by over 80 leading experts in the field, this call to action details what would be required to curtail amphibian declines and extinctions over the next 5 years - and how much this would cost. The Amphibian Specialist Group of the World Conservation Union (IUCN) is spearheading efforts to implement a comprehensive global strategy for amphibian conservation. The Golden Toad of Monteverde, Costa Rica was among the first casualties of amphibian declines. ... Download high resolution version (3593x2400, 1410 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (3593x2400, 1410 KB) Wikipedia does not have an article with this exact name. ... Binomial name Bufo periglenes Savage, 1967 The Golden Toad or Monte Verde Toad (Bufo periglenes) lived in handfulls of places in the Monteverde forest located in Costa Rica, a country in Central America. ... For other uses, see Monteverde (disambiguation). ... For other uses, see Extinction (disambiguation). ... Rainforests are among the most biodiverse ecosystems on earth Biodiversity is the variation of life forms within a given ecosystem, biome or for the entire Earth. ... Habitat destruction is a process of land use change in which one habitat-type is removed and replaced with another habitat-type. ... Air pollution Pollution is the introduction of pollutants (whether chemical substances, or energy such as noise, heat, or light) into the environment to such a point that its effects become harmful to human health, other living organisms, or the environment. ... Alien species redirects here. ... Variations in CO2, temperature and dust from the Vostok ice core over the last 450,000 years For current global climate change, see Global warming. ... The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ... Chytridiomycosis in Atelopus varius - two sporangia containing numerous zoospores are visible Chytridiomycosis is a fatal infectious disease that affects amphibians, caused by the chytrid - Batrachochytrium dendrobatidis . ...

On January 21, 2008, Evolutionarily Distinct and Globally Endangered (EDGE), per chief Helen Meredith identified nature's most endangered species: "The EDGE amphibians are amongst the most remarkable and unusual species on the planet and yet an alarming 85% of the top 100 are receiving little or no conservation attention." The top 10 endangered species (in the List of endangered animal species) include: the Chinese giant salamander, a distant relative of the newt, the tiny Gardiner's Seychelles, the limbless Sagalla caecilian, South African ghost frogs, lungless Mexican salamanders, the Malagasy rainbow frog, Chile's Darwin frog (Rhinoderma rufum) and the Betic Midwife Toad.^[1]^[2]^[3]^[4] is the 21st day of the year in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... An endangered species is a species whose population is so small that it is in danger of becoming extinct. ... For other uses, see Species (disambiguation). ... For other uses, see Amphibian (disambiguation). ... This is a list of endangered animal species according to the World Conservation Union (IUCN) Red List. ... Genera Andrias Cryptobranchus The Giant Salamanders (Cryptobranchidae) are aquatic amphibians found in brooks and ponds in the eastern United States, China and Japan. ... This article is about the animal. ... Distribution of frogs (in black) Suborders Archaeobatrachia Mesobatrachia Neobatrachia - List of Anuran families The frogness babe is an amphibian in the order Anura (meaning tail-less from Greek an-, without + oura, tail), formerly referred to as Salientia (Latin saltare, to jump). ... Binomial name (Philippi, 1902) Rhinoderma rufum is a species of frog in the Rhinodermatidae family. ...

Evolutionary history

The first major groups of amphibians developed in the Devonian Period from fishes similar to the modern coelacanth where the fins had evolved into legs. These amphibians were around five meters long. The land was safe as the giant fishes and sharks in the ocean could not come onto land. However, there were two problems with living out their entire lives on land. Primarily, the food that these amphibians consumed was in the water, but also at this point the skin on most of these amphibians was not water-tight. The Devonian is a major division of the geologic timescale that extends from the end of the Silurian period (360 million years ago (mya)) to the beginning of the Mississippian subperiod of the Carboniferous (408. ... Families See text. ...

In the Carboniferous Period, the amphibians moved up in the food chain and began to occupy the ecological position where we now find crocodiles. These amphibians were notable for eating the mega-insects on land and many types of fishes in the water. Towards the end of the Permian Period and the Triassic Period, the amphibians started having competition with proto-crocodiles which led to their drop in size in the temperate zones or leaving for the poles. (Amphibians were able to hibernate during the winter whereas crocodiles could not, allowing the amphibians in higher latitudes protection from the reptiles.) The Carboniferous is a major division of the geologic timescale that extends from the end of the Devonian period, about 340 million years ago (mya), to the beginning of the Permian period, about 280 mya. ... The Permian is a geologic period that extends from about 280 to 248 million years before the present (mya). ... The Triassic is a Geologic period that extends from about 248 to 202 million years (My or megayears) before the present. ...

Paleontologists once believed that the kind of lifestyle and adaptations that proto-amphibians was similar to the modern mudskipper.^{[citation needed]} (Mudskippers are not closely related to coelocanths.) Genera Apocryptes Apocryptodon Boleophthalmus Oxuderces Parapocryptes Periophthalmodon Periophthalmus Pseudapocryptes Scartelaos Zappa (genus) Mudskippers are members of the subfamily Oxudercinae (tribe: Periophthalmini[1]), within the family Gobiidae (Gobies). ...

Contents

Systems

Reproductive

Conservation

Evolutionary history

See also

References

Further reading

External links