Portal:Amphibians
The Amphibian Portal
Amphibians are ectothermic, anamniotic, four-limbed vertebrate animals that constitute the class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all tetrapods excluding the amniotes (tetrapods with an amniotic membrane, such as modern reptiles, birds and mammals). All extant (living) amphibians belong to the monophyletic subclass Lissamphibia, with three living orders: Anura (frogs and toads), Urodela (salamanders), and Gymnophiona (caecilians). Evolved to be mostly semiaquatic, amphibians have adapted to inhabit a wide variety of habitats, with most species living in freshwater, wetland or terrestrial ecosystems (such as riparian woodland, fossorial and even arboreal habitats). Their life cycle typically starts out as aquatic larvae with gills known as tadpoles, but some species have developed behavioural adaptations to bypass this.
Young amphibians generally undergo metamorphosis from an aquatic larval form with gills to an air-breathing adult form with lungs. Amphibians use their skin as a secondary respiratory interface and some small terrestrial salamanders and frogs lack lungs and rely entirely on their skin. They are superficially similar to reptiles like lizards, but unlike reptiles and other amniotes, require access to water bodies to breed. With their complex reproductive needs and permeable skins, amphibians are often ecological indicators to habitat conditions; in recent decades there has been a dramatic decline in amphibian populations for many species around the globe.
The earliest amphibians evolved in the Devonian period from tetrapodomorph sarcopterygians (lobe-finned fish with articulated limb-like fins) that evolved primitive lungs, which were helpful in adapting to dry land. They diversified and became ecologically dominant during the Carboniferous and Permian periods, but were later displaced in terrestrial environments by early reptiles and basal synapsids (predecessors of mammals). The origin of modern lissamphibians, which first appeared during the Early Triassic, around 250 million years ago, has long been contentious. The most popular hypothesis is that they likely originated from temnospondyls, the most diverse group of prehistoric amphibians, during the Permian period. Another hypothesis is that they emerged from lepospondys. A fourth group of lissamphibians, the Albanerpetontidae, became extinct around 2 million years ago. (Full article...)
Selected frog article
Selected salamander article
The Cryptobranchoidea are a suborder of salamanders found in Asia, European Russia, and the United States. They are known as primitive salamanders, in contrast to Salamandroidea, the advanced salamanders. It has two living subdivisions, Cryptobranchidae (Asian giant salamanders and hellbenders), and Hynobiidae, commonly known as Asian salamanders.
Giant salamanders are obligate paedomorphs with partial metamorphosis, but Asiatic salamander goes through a full metamorphosis. The only known exceptions are the Longdong stream salamander, which has been documented as facultatively neotenic, and the Ezo salamander, where a now assumed extinct population from Lake Kuttarush in Hokkaido had neotenic traits like gills in adults.
The oldest members of the group are known from the Middle Jurassic (Bathonian) aged Yanliao Biota of China. (Full article...)List of selected salamander articles
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Did you know? –
- ... that although it was first classified as a reptile, the extinct genus Batropetes (restoration pictured) is now known to be a microsaur amphibian?
- ... that golden frogs are often mistaken for bronzed frogs?
- ... that the largest amphibian in the world is the Chinese giant salamander (pictured)?
- ...that the Eastern Newt changes its skin colour from bright red to olive green when it becomes an adult, and is known as the red eft before adulthood?
- ... that the East Bay Vivarium is the oldest and largest retail vivarium in the United States?
Selected amphibian type
Toad is a common name for certain frogs, especially of the family Bufonidae, that are characterized by dry, leathery skin, short legs, and large bumps covering the parotoid glands.
A distinction between frogs and toads is not made in scientific taxonomy, but is common in popular culture (folk taxonomy), in which toads are associated with drier, rougher skin and more terrestrial habitats. (Full article...)List of selected amphibian type articles
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Selected toad article
Mertensophryne micranotis is a species of toad in the family Bufonidae. It is found in southeastern Kenya and eastern Tanzania, including Zanzibar and Songo Songo Island.
Its natural habitats are lowland forests, dense woodlands, thickets, and the forest-miombo woodland boundaries. It is regularly seen but difficult to detect. It is probably affected by habitat loss caused by agriculture, wood extraction and human settlement. (Full article...)Selected caecilian article
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