Portal:Amphibians

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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, 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), 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.

The young generally undergo metamorphosis from larva with gills to an adult air-breathing form with lungs. Amphibians use their skin as a secondary respiratory surface 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 water bodies in which to breed. With their complex reproductive needs and permeable skins, amphibians are often ecological indicators; 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 sarcopterygian fish with lungs and bony-limbed fins, features that 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 (mammal predecessors). The origin of modern amphibians belonging to Lissamphibia, which first appeared during the Early Triassic, around 250 million years ago, has long been contentious. However the emerging consensus is that they likely originated from temnospondyls, the most diverse group of prehistoric amphibians, during the Permian period. (Full article...)

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Selected frog article

Dendrobates tinctorius "azureus"

The Neobatrachia (Neo-Latin neo- ("new") + batrachia ("frogs")) are a suborder of the Anura, the order of frogs and toads.

This suborder is the most advanced and apomorphic of the three anuran suborders alive today, hence its name, which literally means "new frogs" (from the hellenic words neo, meaning "new" and batrachia, meaning "frogs"). It is also by far the largest of the three; its more than 5,000 different species make up over 96% of all living anurans.

The differentiation between Archaeobatrachia, Mesobatrachia, and Neobatrachia is based primarily on anatomic differences, especially the skeletal structure, as well as several visible characteristics and behaviors. (Full article...)

List of selected frog articles

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 the Cheat Mountain salamander of West Virginia is the only vertebrate known to be unique to that state?
... that the Permian amphibian Trimerorhachis either brooded young in its mouth or ate them?
... that the Cumberland Dusky Salamander is believed to hybridize with the Ocoee Salamander?
... that female European cave salamanders do not normally eat while they guard their eggs for six months or more?
... that in hot weather, the eastern spadefoot toad (pictured) may aestivate in the deep burrow it has dug?

Selected amphibian type

Various types of frog

A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (coming from the Ancient Greek ἀνούρα, literally 'without tail'). The oldest fossil "proto-frog" Triadobatrachus is known from the Early Triassic of Madagascar, but molecular clock dating suggests their split from other amphibians may extend further back to the Permian, 265 million years ago. Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforest. Frogs account for around 88% of extant amphibian species. They are also one of the five most diverse vertebrate orders. Warty frog species tend to be called toads, but the distinction between frogs and toads is informal, not from taxonomy or evolutionary history.

An adult frog has 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 fresh water and on dry land; some species are adapted for living underground or in trees.

Frogs typically lay their eggs in water. The eggs hatch into aquatic larvae called tadpoles that have tails and internal gills. They have highly specialized rasping mouth parts suitable for herbivorous, omnivorous or planktivorous diets. The life cycle is completed when they metamorphose into adults. A few species deposit eggs on land or bypass the tadpole stage. Adult frogs generally have a carnivorous diet consisting of small invertebrates, but omnivorous species exist and a few feed on plant matter. Frog skin has a rich microbiome which is important to their health. Frogs are extremely efficient at converting what they eat into body mass. They are an important food source for predators and part of the food web dynamics of many of the world's ecosystems. The skin is semi-permeable, making them susceptible to dehydration, so they either live in moist places or have special adaptations to deal with dry habitats. Frogs produce a wide range of vocalizations, 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
Frogspawn
Photo credit: Tarquin
In the life cycle of a frog, a female lays her eggs in a shallow pond or creek, where they will be sheltered from the current and from predators. The eggs, known as frogspawn hatch into tadpoles. The tadpoles develop gradually into adolescent froglets and finally the froglet develops into an adult frog.
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Image 2
Atelopus limosus
Photograph: Brian Gratwicke
A female limosa harlequin frog (Atelopus limosus) in Panama. This endangered species of toad in the family Bufonidae inhabits stream banks in tropical moist lowland forests and rivers of the Chagres watershed. It is found in two colour forms, one in lowlands and one in uplands.
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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
Iberian midwife toad
Photograph: Benny Trapp
The Iberian midwife toad (Alytes cisternasii) is a species of frog in the family Alytidae found in Portugal and western Spain. Its natural habitats are temperate forests and shrubland, Mediterranean-type shrubby vegetation, intermittent rivers and freshwater marshes, pastureland, and aquaculture ponds. The species is affected by habitat loss, and the IUCN lists it as being "Near Threatened".
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Image 5
White's Tree Frog
Illustration credit: Ernst Haeckel
A frog is an amphibian characterized by long hind legs, a short body, webbed digits, protruding eyes and the absence of a tail. Frogs are most noticeable through their call, which can be widely heard during the mating season. It is estimated that up to 20% of amphibian species may care for their young in one way or another, and there is a great diversity of parental behaviours. For example, frogs in the Gastrotheca genus (upper left) carry their eggs in a pouch, and females of the Eleutherodactylus lineatus species (center left) carry their young on their back.
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Image 6
Common Indian Toad
Photo: Lokionly
The Common Indian Toad (Duttaphrynus melanostictus) is native to South Asia. It grows to about 20 cm (8 in) long and breeds during monsoon season. These toads are often seen at night under street lamps especially during times when winged termites swarm. They have been noted to feed on a wide range of invertebrates, including scorpions.
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Image 7
Emerald-eyed tree frog
Photo: Paolo Costa Baldi
The emerald-eyed tree frog (Rana platanera) is a species of frog in the family Hylidae found in South America.
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Image 8
Leaf Green Tree Frog
Photo credit: Froggydarb
A specimen from the "hybrid zone" of the Leaf Green Tree Frog (Litoria phyllochroa) and the Southern Leaf Green Tree Frog (L. nudidigitus), showing physical characteristics of both species. These small stream-dwelling frogs (averaging only 40mm in length), are native to eastern Australia and occur together south of Sydney. The two species are differentiated only by distribution, call and slight differences in flank markings.
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Image 9
Eastern newt
Photo credit: Patrick Coin
A terrestrial subadult Eastern newt or red eft (Notophthalmus viridescens). Salamanders of the family Salamandridae with aquatic adult stages are called newts. Some newts, including the Eastern newt, have a juvenile terrestrial stage called the eft. The red eft has bright aposematic coloration to warn predators of its highly toxic skin.
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Image 10
Vocal sac
Photo: Benny Trapp
An Italian tree frog (Hyla intermedia) with an inflated vocal sac. Vocal sacs, flexible membranes of skin possessed by most male frogs, are generally used to amplify mating or advertisement calls. However, some species in the family Rhinodermatidae may also use the sac to store or transport their tadpoles.
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Image 11
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 12
Common toads in amplexus
Photo: Bernie Kohl
Two common toads (Bufo bufo) in amplexus, a form of pseudocopulation found in amphibians and limulids. A male common toad grasps a female with his front legs as part of the mating process. Common toads stay in amplexus for several days. As the female lays a long, double string of small black eggs, the male fertilises them with his sperm; the gelatinous egg strings, which may contain 3000 to 6000 eggs and be 3 to 4.5 metres (10 to 15 ft) in length, are later tangled in plant stalks.
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Image 13
Fire salamander
Photo: Archaeodontosaurus
The fire salamander (Salamandra salamandra) is a European salamander species with a long lifespan. These nocturnal animals generally eat various insects, spiders, earthworms and slugs, but they also occasionally eat newts and young frogs.
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Image 14
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 15
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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Selected toad article

The bleeding toad, fire toad or Indonesian tree toad (Leptophryne cruentata) is a species of true toad in the amphibian family Bufonidae, endemic to Java, Indonesia. L. javanica was, formerly, synonymous with the bleeding toad prior to its description as a distinct species in 2018, although the degree of differentiation between these species is low. The bleeding toad is listed as a critically endangered species due to a drastic population decline. The factors behind this decline are unclear, but appear consistent (despite ambiguous observations) with the global spread of chytrid fungus, a particularly lethal fungal spore for frogs and toads; once infected, the animals develop a condition known as chytridiomycosis before ultimately dying. it is estimated there are less than 250 individuals of the species. (Full article...)

List of selected toad articles

Selected caecilian article

Chikilidae is a family of Indian caecilians, the 10th and most recent (2012) family of caecilians (legless amphibians) to be identified, although the type species, Chikila fulleri (formerly Herpele fulleri) was first described in 1904. The discovery that this was a separate lineage resulted from genetic analyses of specimens collected during about 250 soil-digging expeditions over five years that covered every Northeast Indian state. A team of biologists led by University of Delhi herpetologist Sathyabhama Das Biju described the family as representing as many as seven species apparently endemic to the region. In September 2012, some of these species were also found in Lawachara National Park in the Sylhet region of northeastern Bangladesh. The family's lineage is believed to have originated in Africa, where their closest living relatives are found.

Chikilids grow to about 4 in (10 cm) in length. They have very limited eyesight and skulls adapted for burrowing. Their eggs hatch into adult caecilians, with no larval stage in between. The mothers stay wrapped around their developing eggs for two to three months, apparently not eating at all during this period.

Until this discovery, only nine families of caecilians were known from across the wet tropical regions of Southeast Asia, India, Sri Lanka, parts of East and West Africa, the Seychelles, Central America and northern and eastern parts of South America. From morphological and DNA analyses, the researchers concluded the new family had evolved independently of other caecilians since the time of the dinosaurs. (Full article...)

List of selected caecilian articles