Portal:Amphibians

The Amphibian Portal

Anaschisma

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, but 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 even 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 lepospondyls. A fourth group of lissamphibians, the Albanerpetontidae, became extinct around 2 million years ago. (Full article...)

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Selected frog article

Cornufer guentheri

The Ceratobatrachidae are a family of frogs found in the Malay Peninsula, Borneo, the Philippines, Palau, Fiji, New Guinea, and the Admiralty, Bismarck, and Solomon Islands. (Full article...)

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Selected salamander article

Tiger salamander

Ambystomatidae is a family of salamanders belonging to the Suborder Salamandroidea in the class Amphibia. It contains two genera, Ambystoma (the mole salamanders) and Dicamptodon (the Pacific giant salamanders). Ambystoma contains 32 species and are distributed widely across North America, while Dicamptodon contains four species restricted to the Pacific Northwest. These salamanders are mostly terrestrial and eat invertebrates, although some species are known to eat smaller salamanders. They can be found throughout the US and some areas of Canada in damp forests or plains. This family contains some of the largest terrestrial salamanders in the world, the tiger salamander and the coastal giant salamander. Some species are toxic and can secrete poison from their bodies as protection against predators or infraspecific competition. Neoteny has been observed in several species in Ambystomatidae, and some of them like the axolotl live all of their lives under water in their larval stage. (Full article...)

List of selected salamander articles
Caudata Cryptobranchoidea Greater siren Salamanders in folklore Salamandroidea Sexual selection in amphibians Sirenidae Urodela

Did you know? – show different entries

...that leopard frogs are an environmental indicator species?
... that Sri Lanka is home to three endemic frog genera: Adenomus, Nannophrys, and Lankanectes?
...that both species of Corroboree frog are critically endangered?

Selected amphibian type

Various kinds of frog

A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order Anura (coming from the Ancient Greek ἀνούρα, literally 'without tail'). Frog species with rough skin texture due to wart-like parotoid glands tend to be called toads, but the distinction between frogs and toads is informal and purely cosmetic, not from taxonomy or evolutionary history.

Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforest and associated wetlands. They account for around 88% of extant amphibian species, and are one of the five most diverse vertebrate orders. The oldest fossil "proto-frog" Triadobatrachus is known from the Early Triassic of Madagascar (250 million years ago), but molecular clock dating suggests their divergence from other amphibians may extend further back to the Permian, 265 million years ago.

Adult frogs have a stout body, protruding eyes, anteriorly-attached tongue, limbs folded underneath, and no tail (the "tail" of tailed frogs is an extension of the male cloaca). Frogs have glandular skin, with secretions ranging from distasteful to toxic. Their skin varies in colour from well-camouflaged dappled brown, grey and green, to vivid patterns of bright red or yellow and black to show toxicity and ward off predators. Adult frogs live in both fresh water and on dry land; some species are adapted for living underground or in trees. As their skin is semi-permeable, making them susceptible to dehydration, they either live in moist niches or have special adaptations to deal with drier habitats. Frogs produce a wide range of vocalisations, particularly in their breeding season, and exhibit many different kinds of complex behaviors to attract mates, to fend off predators and to generally survive. (Full article...)

List of selected amphibian type articles
Toad Salamander Caecilian

Selected images

Image 1
Edible frog
Photograph: Grand-Duc; edit: Niabot
The edible frog (Pelophylax kl. esculentus) is a fertile hybrid of the pool and marsh frogs which is commonly found in Europe. The species is commonly used in food, including the French delicacy frog legs.
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Image 2
Dendrobates azureus
Photo: Quartl
Dendrobates azureus, commonly known as the blue poison dart frog or okopipi, is a poison dart frog found in the forests surrounded by the Sipaliwini Savanna in southern Suriname. Authorities have recently treated it as a variant of Dendrobates tinctorius rather than a distinct species as before.
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Image 3
White's Tree Frog
Photo credit: liquidGhoul
Native to Australia, White's Tree Frog grows up to 10 centimetres in length and is a popular household pet. In captivity, they have an average lifespan of 16 years. Its skin secretions contain caerins, a group of peptides with antibacterial and antiviral properties. Other peptides have been found to destroy HIV without harming healthy T-cells.
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Image 4
Marsh frog
Photograph credit: Charles James Sharp
The marsh frog (Pelophylax ridibundus) is a species of amphibian native to Europe and parts of Asia. It is the largest type of frog in most of its range, growing to a snout-to-vent length of around 100 mm (4 in); tadpoles can reach up to 190 mm (7.5 in) in length, but this usually occurs in places with long winters where the tadpole has time to grow. Marsh frogs hibernate during the winter, either underwater or in burrows, and are able to use the Earth's magnetic field to locate breeding ponds. This marsh frog was photographed in Kampinos National Park, Poland.
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Image 5
Red-eyed Tree Frog
Photo credit: Carey James Balboa
The Red-eyed Tree Frog (Agalychnis callidryas) is a small-sized tree frog, reaching lengths of about 5 to 7 centimeters (3 inches), native to Neotropical rainforests in Central America. They are not poisonous and rely on camouflage to protect them. During the day, they remain motionless with their colorful parts hidden. Thus, they appear almost completely green, and well hidden among the foliage.
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Image 6
Southern brown tree frog
Photograph: JJ Harrison
The southern brown tree frog (Litoria ewingii) is a species of tree frog native to Australia found in a wide range of habitats. Reaching 45 millimetres (1.8 in), this species is generally brown, but green and green-striped morphs are also recorded.
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Image 7
Agile frog
Photograph credit: Petar Milošević
The agile frog (Rana dalmatina) is a species of true frog in the family Ranidae. Native to central and southern Europe, its brownish dappled colouring helps to conceal it among the leaf litter on the forest floor. This frog, about 5 cm (2.0 in) long, was photographed in the Golovec Forest in Slovenia.
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Image 8
Ecnomiohyla rabborum
Photograph: Brian Gratwicke
Rabbs' fringe-limbed treefrog (Ecnomiohyla rabborum) is a large species of frog originally found in the forest canopies of central Panama. Only discovered in 2005, the species is thought to be extinct in the wild; only one specimen, a male at the Atlanta Botanical Garden, survives.
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Image 9
Albanian water frog
Photograph: Benny Trapp
The Albanian water frog (Pelophylax shqipericus) is a species of true frog in the family Ranidae. It is native to Albania and Montenegro, where it lives in aquatic environments. The frogs are medium-sized. Males sometimes bear a distinctive bright green stripe down the length of the backbone, but otherwise are green to light brown in overall colouring with large black or dark brown spots. Females are olive green or light brown in colour and also bear brown or black large spots. The species is endangered and known populations are currently in decline.
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Image 10
Common frog
Photo: Richard Bartz
The common frog (Rana temporaria) is found throughout much of Europe. Adults have a body length of 6 to 9 cm (2.4 to 3.5 in) and vary in colour, with the ability to lighten and darken their skin to match their surroundings. They will feed on any invertebrate of a suitable size and, apart from the breeding season, live solitary lives.
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Image 11
Spanish painted frog
Photograph: Benny Trapp
The Spanish painted frog (Discoglossus jeanneae) is a species of frog in the family Alytidae. Endemic to Spain, it mostly lives in open areas, pine groves and shrublands. It feeds mostly on insects and worms.
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Image 12
Marsh frog
Photo: Marie-Lan Nguyen
The marsh frog (Pelophylax ridibundus) is a species of true frog and the largest frog native to Europe; females of this sexually dimorphic species may be up to 17 centimetres (6.7 in) long. The marsh frog feeds mainly on insects, but it also eats smaller amphibians, fish, and rodents.
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Image 13
Panamanian golden frog
Photograph: Brian Gratwicke
The Panamanian golden frog (Atelopus zeteki) is a rare species of toad endemic to Panama. First described by Emmett Reid Dunn in 1933, this species was found close to mountain streams on the eastern side of the Tabasará mountain range in Coclé and Panamá Provinces, but is now critically endangered and possibly extinct in the wild.
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Image 14
Blue Mountains Tree Frog
Photo: Benjamint444
The Blue Mountains Tree Frog (Litoria citropa) is a moderate-sized species of tree frog, up to about 60 mm (2.4 in) in length. It is native to coastal and highland areas of eastern Australia, especially in the Blue Mountains, hence its name.
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Image 15
Rana clamitans
Photo credit: Derek Ramsey
The American Green Frog (Rana clamitans) is native to the eastern half of the United States and Canada. Green frogs live wherever there is shallow freshwater: ponds, road-side ditches, lakes, swamps, streams and brooks. The green frog is abundant wherever it occurs.
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Selected toad article

The Korean water toad, Korean toad, water toad, or Stejneger's toad (Bufo stejnegeri), is a species of toad found in East Asia. Two distinct populations are known to exist, one in eastern Liaoning province of northeastern China, and one in the central mountains of the Korean Peninsula. Within South Korea, it is found in eastern Gyeonggi (specifically Gapyeong) and also in Gangwon-do (particularly the Odaesan mountain complex). In addition, it is expected that there are or have been additional populations in the region between central Korea and Liaoning.

The classification of the Korean water toad into the genus Bufo was challenged in a 2006 paper. However, no alternative classification was proposed and the species is at present provisionally allocated to Bufo.

The Korean water toad is found inland, at elevations from 200 to 700 meters above sea level. As its name suggests, it favors water, and is typically found in wooded riparian areas. Breeding and egg-laying take place in the waters of streams and rivers. Bufo stejnegeri exhibits specific behaviors during amplexus and egg-laying behavior that make it distinct from other species. Bufo stejnegeri has unique ecology for a toad because they are semi-aquatic and breed in lotic environments. Between November and January, males and females enter streams and immediately begin amplexus. They stay in amplexus for 3–6 months in frozen-over streams until spring spawning (March–April) and lay eggs in fast-flowing streams under rocks. The water toad is typically nocturnal, but is also active during the day during the summer rains. (Full article...)

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Selected caecilian article

The Grandisoniidae are a family of common caecilians found in Africa, Seychelles and India. Like other caecilians, they superficially resemble worms or snakes. The family was formerly known as Indotyphlidae. (Full article...)

List of selected caecilian articles