Portal:Amphibians
Wikipedia portal for content related to Amphibians / From Wikipedia, the free encyclopedia
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List of selected salamander articles |
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List of selected amphibian type articles |
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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), 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...)
Selected frog article
Ptychadenidae is a family of frogs commonly known as the grassland frogs. These frogs occur in Sub-Saharan Africa.
Ptychadenidae was previously considered to be a tribe or subfamily in the family Ranidae, but its position as a separate family is now well established. (Full article...)Selected salamander article
Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten extant salamander families are grouped together under the order Urodela from the group Caudata. Salamander diversity is highest in eastern North America, especially in the Appalachian Mountains; most species are found in the Holarctic realm, with some species present in the Neotropical realm.
Salamanders never have more than four toes on their front legs and five on their rear legs, but some species have fewer digits and others lack hind limbs. Their permeable skin usually makes them reliant on habitats in or near water or other cool, damp places. Some salamander species are fully aquatic throughout their lives, some take to the water intermittently, and others are entirely terrestrial as adults.
This group of amphibians is capable of regenerating lost limbs as well as other damaged parts of their bodies. Researchers hope to reverse engineer the regenerative processes for potential human medical applications, such as brain and spinal cord injury treatment or preventing harmful scarring during heart surgery recovery. The remarkable ability of salamanders to regenerate is not just limited to limbs but extends to vital organs such as the heart, jaw, and parts of the spinal cord, showing their uniqueness compared to different types of vertebrates. This ability is most remarkable for occurring without any type of scarring. This has made salamanders an invaluable model organism in scientific research aimed at understanding and achieving regenerative processes for medical advancements in human and animal biology. (Full article...)Did you know? – show different entries
- ... that the Bocaina tree frog (pictured) has green bones and muscles?
- ... that Colombia has the greatest variety of amphibian species of any country in the world?
- ...that prehistoric frog Beelzebufo may have grown to over 40 cm (16 in)* (restoration pictured), larger than any living frogs, and is called "the Frog from Hell" by the media?
- ... that the female Black Mountain Salamander broods her eggs?
- ... that the Carpathian newt sometimes hybridises with the smooth newt?
Selected amphibian type
Caecilians (/sɪˈsɪliən/; New Latin for 'blind ones') are a group of limbless, vermiform (worm-shaped) or serpentine (snake-shaped) amphibians with small or sometimes nonexistent eyes. They mostly live hidden in soil or in streambeds, and this cryptic lifestyle renders caecilians among the least familiar amphibians. Modern caecilians live in the tropics of South and Central America, Africa, and southern Asia. Caecilians feed on small subterranean creatures such as earthworms. The body is cylindrical and often darkly coloured, and the skull is bullet-shaped and strongly built. Caecilian heads have several unique adaptations, including fused cranial and jaw bones, a two-part system of jaw muscles, and a chemosensory tentacle in front of the eye. The skin is slimy and bears ringlike markings or grooves and may contain scales.
Modern caecilians are a clade, the order Gymnophiona' /ˌdʒɪmnəˈfaɪənə/ (or Apoda /ˈæpədə/), one of the three living amphibian groups alongside Anura (frogs) and Urodela (salamanders). Gymnophiona is a crown group, encompassing all modern caecilians and all descendants of their last common ancestor. There are more than 220 living species of caecilian classified in 10 families. Gymnophionomorpha is a recently coined name for the corresponding total group which includes Gymnophiona as well as a few extinct stem-group caecilians (extinct amphibians whose closest living relatives are caecilians but are not descended from any caecilian). Some palaeontologists have used the name Gymnophiona for the total group and the old name Apoda for the crown group'. However, Apoda has other even older uses, including as the name of a genus of Butterfly making its use potentially confusing and best avoided. 'Gymnophiona' derives from the Greek words γυμνος / gymnos (Ancient Greek for 'naked') and οφις / ophis (Ancient Greek for 'snake'), as the caecilians were originally thought to be related to snakes and to lack scales.
The study of caecilian evolution is complicated by their poor fossil record and specialized anatomy. Genetic evidence and some anatomical details (such as pedicellate teeth) support the idea that frogs, salamanders, and caecilians (collectively known as lissamphibians) are each others' closest relatives. Frogs and salamanders show many similarities to dissorophoids, a group of extinct amphibians in the order Temnospondyli. Caecilians are more controversial; many studies extend dissorophoid ancestry to caecilians. Some studies have instead argued that caecilians descend from extinct lepospondyl or stereospondyl amphibians, contradicting evidence for lissamphibian monophyly (common ancestry). Rare fossils of early gymnophionans such as Eocaecilia and Funcusvermis have helped to test the various conflicting hypotheses for the relationships between caecilians and other living and extinct amphibians. (Full article...)Selected images
- Image 1Photograph: Benny TrappThe 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".
- Image 2In 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.
- Image 3Photo credit: FroggydarbA 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.
- Image 4Photo credit: Fir0002The Eastern Banjo Frog (Limnodynastes dumerilli) is native to eastern Australia and has been introduced to New Zealand. The frog is also commonly called the pobblebonk after its distinctive "bonk" call, which is likened to a banjo string being plucked. Adults are roughly seven to eight cm long.
- Image 5Photo: Richard BartzThe 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.
- Image 6Photo: QuartlDendrobates 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.
- Image 7The emerald-eyed tree frog (Rana platanera) is a species of frog in the family Hylidae found in South America.
- Image 8Photograph: JJ HarrisonThe 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.
- Image 9The 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.
- Image 10Photograph credit: Petar MiloševićThe 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.
- Image 11Photo credit: LiquidGhoulThe Red-eyed Tree Frog (Litoria chloris) is a species of tree frog native to eastern Australia; ranging from north of Sydney to Proserpine in mid-northern Queensland. These frogs typically reach a size of 65 millimetres (2.6 in). Its skin secretions have been found to destroy HIV, without harming healthy T cells.
- Image 12Photo: Benny TrappAn 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.
- Image 13Photo: Charles H. Smith, USFWSThe golden toad (Bufo periglenes) is an extinct species of true toad that was once abundant in a small region of high-altitude cloud-covered tropical forests, about 30 km2 (12 sq mi) in area, above the city of Monteverde, Costa Rica. The last reported sighting of a golden toad was on 15 May 1989. Its sudden extinction may have been caused by chytrid fungus and extensive habitat loss.
- Image 14Photo: LokionlyThe 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.
- Image 15Photograph: Benny TrappThe Epirus water frog (Pelophylax epeiroticus) is a species of frog in the family Ranidae. It is found in western Greece, including Corfu, and the southern areas of Albania. The species is collected from the wild for human consumption.
Selected toad article
The neural basis of prey detection, recognition, and orientation was studied in depth by Jörg-Peter Ewert in a series of experiments that made the toad visual system a model system in neuroethology (neural basis of natural behavior). He began by observing the natural prey catching behavior of the common European toad (Bufo bufo).
Ewert's work with toads yielded several important discoveries (Ewert 1974, 2004). In general, his research revealed the specific neural circuits for recognition of complex visual stimuli. Specifically, he identified two main regions of the brain, the tectum and the thalamic-pretectal region, that were responsible for discriminating prey from non-prey and revealed the neural pathways that connected them. Furthermore, he found that the neural mechanisms are plastic and adaptable to varying environments and conditions (Carew 2000; Zupanc 2004). (Full article...)Selected caecilian article
Typhlonectes (from Greek: τῠφλός tuphlós, 'blind' and Greek: νηκτῆς nēktês, 'swimmer') is a genus of caecilians in the family Typhlonectidae. These fully aquatic amphibians are found in the Amazon Basin and Northern South America, and typically range between 30 and 60 cm (12–24 in) in length.
The genus contains two species:
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