View source for Amphibian

{{automatic taxobox
| name = Amphibia
| fossil_range = late [[Devonian]]–[[present]], fossil range 370 mya to present
| image = Amphibians.png
| image_upright = 1.15
| image_alt = Collage of amphibians
| image_caption = Clockwise from top right: ''[[Seymouria]]'', Mexican burrowing [[caecilian]], eastern [[newt]] and leaf green [[tree frog]]
| taxon = Amphibia
| authority = [[John Edward Gray|Gray]] 1825
| subdivision_ranks = Subclasses
| subdivision = * {{extinct}}[[Temnospondyli]]
* [[Lissamphibia]] (modern amphibians)
}}
[[File:Eryops - National Museum of Natural History - IMG 1974.JPG|right|300px|thumb|''[[Eryops]]'', typical of the large-size early amphibians 310–295 million years ago]]

'''Amphibians''' are members of the [[class (biology)|class]] '''Amphibia'''. The living ones are [[frog]]s (including [[toad]]s), [[salamander]]s (including [[newt]]s) and [[caecilian]]s. They are [[tetrapod|four-legged]] [[vertebrate]]s which are [[Ectotherm|cold blooded]].

Amphibians lay their eggs in water, usually in a [[foam]] [[nest]]. After [[wikt:hatch|hatching]] they are [[tadpole]]s, which live in the water and have [[gill]]s. The tadpoles change into adults in a process called [[metamorphosis]].  When they are adult, they have [[lung]]s to breathe instead of gills, and legs. Adult amphibians also use their skin to take in [[oxygen]], and some [[species]] of salamanders do not have lungs.

The earliest amphibians [[evolution|evolved]] in the [[Devonian]] from [[sarcopterygii|lobe-finned]] [[fish]] which had jointed leg-like fins with digits. They could crawl along the sea bottom. Some had developed primitive lungs to help them breathe air when the stagnant pools of the Devonian [[swamp]]s were low in [[oxygen]]. They could also use their strong fins to hoist themselves out of the water and onto dry land if necessary.<ref name=Jen>Clack, Jennifer A. 2002. ''Gaining ground: the origin and evolution of tetrapods''. Indiana University Press, Bloomington IN. {{ISBN|0-253-34054-3}}</ref><ref name=Bob/>

For tens of millions of years, during the [[Carboniferous]] and early [[Permian]], amphibia were [[top predator]]s on land, especially in the low-lying tropical river systems.  In drier conditions, they were less effective, and the ancestors of mammals and reptiles (the [[Synapsid]]s and [[Sauropsid]]s) gradually took over the land. They laid [[cleidoic egg]]s, which had hard shells, and could be laid out of water. Most of the early large amphibians went [[extinct]] in the [[Triassic]] period; a few survived to the [[Lower Cretaceous]].<ref name=Bob>Carroll, Robert 2009. ''The rise of amphibians: 365 million years of evolution''. Baltimore: The Johns Hopkins University Press. {{ISBN|978-0-8018-9140-3}}</ref>

The only living amphibiana today are the [[Lissamphibia]]. These include the [[Anura]] (frogs and toads), [[Caudata]] (salamanders and newts) and [[Gymnophiona]] (caecilians). They are all rather small, compared with mammals or reptiles. The smallest frog and vertebrate in the world is the [[Paedophryne amauensis|New Guinea frog]] (''Paedophryne amauensis''). The biggest amphibian is the [[Chinese giant salamander]] (''Andrias davidianus'').

Amphibia are found everywhere in the world, except [[Antarctica]], and there are about 5,565 different species: 88% of them are in the [[Anura]].<ref name="Pou92">{{cite book |title=Herpetology |last=Pough F.H. | display-authors = etal |year=2003 |publisher= 3rd ed, Benjamin Cummings |isbn=0131008498 |page= }}</ref> In number of species, they are more successful than [[mammal]]s, though they occupy a smaller range of [[habitat]]s. However, it is said that amphibian populations have been [[wikt:decline|declining]] all over the world.<ref name="decline"/> Conservation is therefore an important concern.

== Living amphibia ==

*[[Anura]]: [[Frog]]s (including toads)
*[[Caudata]]: [[Salamander]]s (including [[newt]]s)
*[[Gymnophiona]]: Legless amphibia, similar to [[earthworm]]s or [[snake]]s

=== Adaptations ===
==== Respiration ====
Amphibians like to live near [[freshwater]] in warm weather. There have also been species which live in [[forest]]s, [[desert]]s and [[arctic]] conditions. Adult amphibians use lungs, and they also get oxygen through their skin, so long as it is [[wikt:moist|moist]].<ref name=duel>Duellman, William E. & Linda Trueb 1994. ''Biology of amphibians''. Johns Hopkins University Press. {{ISBN|978-0-8018-4780-6}}</ref>

==== Defences ====
Amphibians may be [[camouflage]]d in brown and green, and if so they are [[prey]] for birds and reptiles. Their colour gives them [[camouflage]], which is their main defence.

Alternatively, many other amphibia have [[toxic]] skin, which is [[wikt:harmful|harmful]] to predators. These are [[poisonous]] to eat. This is an important [[defence against predation]]. Connected to this is the use of [[warning colouration]]. They may be in vivid colours of red, black, and yellow. Research into the [[rough-skinned newt]] and the [[garter snake]] shows this is a typical case of [[co-evolution]]. Where they live in the same area, the newts get more poisonous, and the snakes develop more resistance to the poison.<ref>[http://www.sciencedaily.com/releases/2008/03/080311075326.htm Science Daily]</ref><ref>[http://www.gartersnake.info/news/garter_snakes_w.php Garter snake info]</ref><ref>Geffeney, Shana L. | display-authors = etal 2005. Evolutionary diversification of TTX-resistant sodium channels in a predator-prey interaction. ''Nature'' '''434''': 759–763.</ref>

==== Sight ====
Amphibians have [[colour vision]] and depth of focus for clear sight. They also have eyelids, glands and ducts which keep the eyes moist. These are [[adaptation]]s to life on land: amphibia were the first vertebrates to have these features.

=== Development ===
Some amphibia, such as the frog known as the [[common coquí]], lay eggs out of water (in this case, on palm leaves). The eggs develop directly into adult frogs, by-passing the tadpole stage. Others, like [[mudpuppies]] and [[olm]]s, have a different development. In a process called [[neoteny]], they become sexually developed as tadpoles with gills. They continue to live in the water.

== Anura ==
{{main|Anura}}
[[File:Teichfrosch.jpg|thumb|Frogs such as this [[edible frog]] has smooth (soft) wet skin]]
[[File:Bufo speciosus.jpg|thumb|This [[Texas toad]] has rough (hard) dry skin]]

The [[order (biology)|order]] Anura includes the frogs and toads. There is no fundamental difference between frogs and toads. Frogs have a short body, webbed digits (fingers or toes), protruding eyes, forked tongue and no tail. They are exceptional jumpers: many of their features, particularly their long, powerful legs, are adaptations to improve jumping performance. They often live in semi-aquatic or inhabit humid areas.<ref name=Z>Zweifel, Richard G; Cogger H.G. & Zweifel R.G. 1998. ''Encyclopedia of reptiles and amphibians''. San Diego: Academic Press. pp. 91–92. {{ISBN|0-12-178560-2}}</ref>

A popular distinction is often made between frogs and toads on the basis of their appearance. Toads' warty skin is an [[adaptation]] for making their [[toxic]] [[slime]]. Apart from these glands, their skin is dry, and that is an adaptation to drier habitats. These features have evolved a number of times independently: [[convergent evolution]]. The distinction has no taxonomic basis. The only family exclusively given the common name "toad" is [[Bufonidae]] (the "true toads"), but many species from other families are commonly called "toads".<ref name=Z/>

== Caudata ==
[[File:Feuer Salamander 2.jpg|230px|thumb|This [[fire salamander]] has yellow and black stripes along its body: typical [[warning colouration]].]]
[[File:Chinese Fire Bellied Newts 2.JPG|right|230px|thumb|[[Chinese fire-bellied newt]]s has red stripes on their front body, which they can raise when attacked. This is also warning colouration.]]

The order Caudata is the [[salamander]]s.

[[Newt]]s are salamanders which spend their life in the water even though they are adults. They are classified in the [[subfamily]] Pleurodelinae of the family [[Salamandridae]].

[[Respiration (physiology)|Respiration]] differs between species of salamanders. Species that lack lungs respire through [[gill]]s. In most cases, these are external gills, visible as tufts on either side of the head. Some salamanders that are terrestrial have [[lung]]s that are used in respiration, although these are simple and sac-like, unlike the more complex organs found in [[mammal]]s. Many species, such as the [[Olm]], have both lungs and gills as adults.<ref name="EoR">Cogger, Harold G. ed 1998. ''Encyclopedia of reptiles and amphibians''. San Diego: Academic Press. {{ISBN|0-12-178560-2}}.</ref>

Some terrestrial species lack both lungs and gills and perform gas exchange through their skin. Even some species with lungs also respire through the skin in this manner.

The skin of salamanders secretes [[mucus]]. This helps to keep the animal moist when on dry land, keeps their salt balance while in water, and lubricates during swimming. Salamanders also secrete [[poison]] from glands in their skin, and some additionally have skin glands for secreting courtship [[pheromone]]s.<ref name=EoR/>

[[Axolotl]]s, from  the genus ''[[Ambystoma]]'' (or mole salamanders),  are [[neoteny|neotenic]] amphibians. This means they get to sexual maturity and reproduce while still in a [[larva]]l form.

=== Defence mechanisms ===
Most salamanders and newts have some [[defence against predators]], usually a poison which makes them uneatable. Their bright colours are [[warning colouration]]. If, instead, they are [[camouflage]]d, this means they are probably not protected by a [[toxin]].
 
The second line of defence is to shed their tail, which can grow again. The tail wriggles a bit, attracts the predator while the business part of the salamander moves off.

=== Other characteristics ===
There are over 350 [[lungless salamanders]]. Most of them are terrestrial and are active in daytime. Lungless salamanders may communicate with their nose.<ref name=Steb/><sup>p168</sup> [[Slender salamander]]s are found in the [[Pacific Coast]]. They are sometimes called "worm salamanders". This is because they have slimmer (skinny) bodies than most salamanders.<ref name=Steb>Stebbins, Robert Cyril 2003. A field guide to western reptiles and amphibians. Houghton Mifflin Harcourt. {{ISBN|0395982723}}</ref><sup>p182</sup> If touched, slender salamanders will [[wikt:bounce|bounce]] on the ground and then run away.

== Gymnophiona ==
[[File:Beddome's Caecilian.jpg|thumb|[[Beddome's Caecilian]], like all other caecilians, do not have feet or limbs.]]

The order [[Gymnophiona]] includes the caecilians.<ref> Nussbaum, Ronald A; Cogger H.G. & Zweifel R.G. eds 1998. ''Encyclopedia of reptiles and amphibians''. San Diego: Academic Press. pp. 52–59. ISBN 0-12-178560-2</ref> These are long, cylindrical, limbless animals that look like [[snake]]s or [[Annelid|worms]]. Their skin has circular folds, increasing their similarity to the segments of earthworms. Some are aquatic, but most live underground in burrows they hollow out. Many caecilians give birth to live young. In species which lay eggs, the eggs may undergo metamorphosis before they hatch. Caecilians are found in tropical Africa, Asia and Central and South America. There are 171 different species.

Their skins make a mucus that makes them slippery enough to slip through the earth.  They can make a toxic material in their skins, as many frogs and toads do.<ref name="EurekaFang">{{cite press release|date=July 3, 2020|accessdate=July 7, 2020|title='Fang'tastic: researchers report amphibians with snake-like dental glands |publisher=Eurekalert|author=Utah State University|url=https://www.eurekalert.org/pub_releases/2020-07/usu-rr063020.php}}</ref><ref name="OralVenom">{{cite journal|publisher=Cell Press|accessdate=July 7, 2020|date=July 3, 2020|title=Morphological Evidence for an Oral VenomSystem in Caecilian Amphibians|author1=Pedro Luiz Mailho-Fontana|author2=Marta Maria Antoniazzi|author3=Cesar Alexandre|author4=Daniel Carvalho Pimenta|author5=Juliana Mozer Sciani|author6=Edmund D. Brodie, Jr.|author7=Carlos Jared|journal=iScience|volume=23|issue=7|page=101234|url=https://www.cell.com/iscience/pdf/S2589-0042(20)30419-3.pdf?_returnURL=https%3A%2F%2Ffanyv88.com%3A443%2Fhttps%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2589004220304193%3Fshowall%3Dtrue|doi=10.1016/j.isci.2020.101234|pmid=32621800|pmc=7385905|bibcode=2020iSci...23j1234M}}</ref>

== Reproduction ==
[[File:Hylarana aurantiaca amplexus.jpg|thumb|A pair of ''[[Hylarana aurantiaca]]'' mating]]

Amphibians are the only vertebrates to go through [[metamorphosis]]. This means that their young look different from their adult.<ref name=Sal>Morgan, Sally 2004. ''Amphibians''. Heinemann-Raintree. {{ISBN|1410910466}}</ref><sup>p8</sup> Amphibians usually reproduce in early spring to late summer, though some reproduce in winter and fall.<ref name=Steb/><sup>p156</sup> Most frogs and toads, such as the [[common frog]] (''Rana temporalis''), gather in large groups to ponds, rivers, swamps and lakes to breed.<ref name=Sal/><sup>p10</sup> Male frogs and toads may [[wikt:croak|croak]] to attract a female. When a female frog has chosen a mate, the male frog hops on top of her. They swim together as she lay eggs in the water.<ref name=Royston>Royston, Angela 2004. ''Amphibians''. Black Rabbit. ISBN 1932333339<sup>p7</sup></ref> Sometimes, males fight to mate with a female.<ref name=Royston/><sup>p7</sup> Frogs can lay up to 100 to 60,000 eggs in one [[wikt:clutch|clutch]]. This is called "frogspawn".

It is a fundamental feature of amphibia that their reproduction is, one way or another, tied to water. This is because their eggs, although covered by jelly, cannot survive long in dry conditions.

=== Eggs ===
[[File:Frogspawn closeup.jpg|thumb|Frogs eggs are called "frogspawn"]]
[[File:Frog eggs.jpg|right|220px|thumb|Some amphibians lay eggs that are very clear. This makes it easy to watch a tadpole grow inside its egg]]

Most female amphibians lays her eggs in water. Males release [[sperm]] to [[fertilize]] them. The eggs are laid one by one or in [[wikt:batches|batches]]. Batches of eggs can look like a long [[chain]] or a ball of foam. They may [[wikt:wrap|wrap]] their eggs around plants in the water. They do this so their eggs will not [[wikt:drift|drift]] away.<ref name=Sal/><sup>p8</sup>

Tree frogs usually lay their eggs on a [[leaf]] in a rainwater pool. Bullfrogs, such as the male [[American bullfrog]] and the male African bullfrog, stay with their tadpoles and protect them from predators. They also move their tadpoles by using their nose to dig a [[wikt:channel|channel]] to another place where there is more water.<ref name=Sal/><sup>p9</sup> They do this so their tadpoles do not dry up. Most amphibians leave their eggs to look after themselves. Fish and other animals eat most of their eggs. Male [[midwife toad]]s carry their eggs on their backs. When they are ready to hatch, the toad goes back to the water and release them.<ref name=Royston/><sup>p10</sup>

=== Tadpoles ===
[[File:Litoria xanthomera tadpole.jpg|thumb|This [[orange-thighed Frog]] tadpole has only a head and a tail. It will grow back legs and front hands in a couple of weeks. It will then lose its tail and become a young frog.]]

Tadpoles do not have lungs when they hatch and instead have [[gill]]s. Because gills have a large [[surface area]], tadpoles can get more oxygen by using them. Young tadpoles have their gills [[wikt:expose|exposed]]. When they get older, their gills are covered over by skin.<ref name=Sal/><sup>p6</sup>  When they hatch, tadpoles eat constantly. The tadpoles eat what is left of their eggs, this is usually their first food.<ref name=Sal/><sup>p8</sup>

Frog, toad and newt tadpoles eat [[plant]]s such as [[algae]] and [[pondweed]] or [[Filter feeder|filter feed]]. When they get older, they may start to feed on tiny animals in the water. Salamander tadpoles and [[surinam horned toad]] tadpoles are [[carnivorous]] throughout their tadpole stage.<ref name=Sal/><sup>p9</sup> Surinam horned toad tadpoles are very [[wikt:aggressive|aggressive]]. They eat other tadpoles if food is nowhere to be found. The eggs of the spadefoot toad hatches in three days. Their tadpoles complete their metamorphosis in six to eight days. This is because spadefoot toads lay their eggs in places where water will dry up soon.<ref name=Sal/><sup>p13</sup>

Tadpoles of frogs and toads start to grow their back legs first. They then grow front legs a few weeks later. When tadpoles grow their limbs they are called "froglets". This is because they look rather like a smaller version of adult frogs and toads. Tadpoles will also start to grow a backbone after growing their front limbs. After this, their mouths get bigger and their eyes will stick out more. After a tadpole has grown its hands, their tails continue to get shorter until there is nothing left of them.<ref name=Sal/><sup>p11</sup>

== Habitats ==
[[File:Frog in garden pond in Davington, Faversham - geograph.org.uk - 1377073.jpg|thumb|Most frogs like to spend their time in the water hiding near aquatic plants]]
[[File:Alpenmolch Alpine Newt Triturus alpestris.jpg|right|220px|thumb|This [[Alpine newt]] is [[basking]] on a rock. It does this to get heat from the sun]]

Salamanders and newts can be found living in [[stream]]s. Salamanders can be found in [[log|rotten log]]s, holes or underground places that are wet such as under leaves.<ref name=Steb/><sup>p152</sup> Web-toed salamanders live in habitats where there are a lot of rocks. They like to hide under rocks and stones.<ref name=Steb/><sup>p195</sup> The tailed frogs, like to live in cold water habitats.<ref name=Steb/><sup>p199</sup> In their habitat, amphibians like to live where there are a lot of places to hide. These include nearby small trees, logs and plants. While underwater they like to hide near aquatic plants and rocks. Tree and dart frogs like to live in forests on trees, plants and on the ground under leaves.

Some amphibia can be found living in the [[desert]] or the [[arctic]].<ref name=Sal/><sup>p12</sup> The [[desert froglet]] lives in the desert. They are only active at night, when temperatures are much cooler. It rarely rains in the desert and because of this, desert frogs will [[burrow]] to keep cool. They use their mucus to keep them wet. They will spread it all over their bodies. The mucus will harden to keep the water it produces from escaping. Once the desert frog has done this, it will stay in its [[cocoon]] and will not move. They will stay like this for several months to years until a rainstorm. Desert frogs and toads lose water more quickly. The spadefoot toad will [[spit]] on the ground. Once they have done this, they will lay on it. Their bodies will take in the water. Their bodies are thin and have a lot of [[blood vessel]]s, this helps them to be able to take water through their skin. The [[California newt]] can survive a [[fire]] by spreading its mucous over its body.<ref name=Sal/><sup>p12</sup>

Arctic frogs such as the [[wood frog]], [[moor frog]] and the common frog has to live with freezing temperatures for a long time. They will burrow in places where they can get into a cocoon. Like every living organisms, amphibians must have water to survive. Amphibians however, need freshwater. Some frogs such as burrowing frogs can [[wikt:store|keep]] water in their [[bladder]]s. This allows them to stay underground without drying up. The [[crab-eating frog]] lives near water that is somewhat [[saltwater|salty]]. They will eat [[crab|saltwater crabs]]. Torrent salamanders lives in cold waters. Because of this they have shorter lungs. Short lungs helps them to float easily.

=== Distribution ===
Amphibia are world-wide, though restricted in distribution by their need for moist or watery habitats to reproduce.

== Anatomy ==
=== Skin ===
[[File:DEN azu.jpg|thumb|This poison dart frog's skin is blue. This color warns animals that they are toxic]]
[[File:Flickr - Furryscaly - Not a Hypnotoad.jpg|thumb|Most amphibians have a good sense of smell. Their eyes have color and clear vision]]

Many amphibia have secretions in their skin which makes them toxic. They do not produce toxins themselves.<ref name="pmid15520388">{{cite journal |author=Dumbacher J.P. | display-authors = etal|title=Melyrid beetles (Choresine): a putative source for the batrachotoxin alkaloids found in poison-dart frogs and toxic passerine birds |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=101 |issue=45 |pages=15857–60 |date=November 2004 |pmid=15520388 |pmc=528779 |doi=10.1073/pnas.0407197101| bibcode = 2004PNAS..10115857D| doi-access = free}}</ref> They get toxins from what they eat. They eat insects in their habitat. These insects get the poison from a plant. The toxin has been discovered in beetles.<ref name="pmid15520388"/> This means that they are likely the cause of poisons found in amphibians. Amphibians do not produce batrachotoxin in captivity, which means that it is not harmful to touch them. The [[American Indian]] tribe [[comechingón]]s used the toxins of the [[arrow dart frogs]] when [[hunt]]ing.<ref name="pmid15520388"/>

Newts in the genus ''[[Taricha]]'' has a poison called [[tetrodotoxin]], a [[neurotoxin]]. Scientists believe that toxins in newts are caused by [[bacteria]] in the genera ''Pseudoalteromonas'', ''[[Pseudomonas]]'' and ''[[Vibrio]]''. Because of this, the newts do not have a lot of predators. However, some species of snakes have develop a [[Warning colouration#Toxin resistance|resistance]]. This means that they can eat newts without the toxin hurting them. It is a case of [[co-evolution]].

=== Senses and skeletal system ===
Amphibians' eyes have [[Eyelid|lids]], [[gland]]s and [[duct]]s. They have good colour vision<ref name=EBAmphibia>{{cite encyclopedia |url=http://www.britannica.com/EBchecked/topic/21445/amphibian/ |title=Amphibian |author=Duellman, William E.; Zug, George R. |year=2012 |encyclopedia=Encyclopædia Britannica |accessdate=2012-03-27}}</ref>  Caecilian eyes are small and dark. Most of them are [[blind]]. Most amphibians have a good sense of [[Olfaction|smell]], even underwater.

The [[skeleton|skeletal system]] of amphibians are similar to other four-legged animals. They have a [[spine]], [[rib cage]], long bones such as the [[humerus]] and [[femur]]. They also have short bones such as the [[phalanges]], [[Metacarpus|metacarpals]], and [[metatarsals]]. Most amphibians have four limbs, except for caecilians. The bones in amphibians are [[wikt:hollow|hollow]] and do not weigh much.<ref name=AmphibAnat>{{cite web |url=http://www.amphibanat.org/ |title=AmphibAnat |author=Maglia A.M. |display-authors=etal |year=2007 |work=The amphibian anatomical ontology web project. |accessdate=2012-03-25 |archive-date=2012-01-16 |archive-url=https://web.archive.org/web/20120116235754/http://www.amphibanat.org/ |url-status=dead }}</ref>

== Diet ==
[[File:Cambodia Frog Eating Frog.JPG|thumb|Amphibians are predatory animals. If there is no food to be found, they will eat each other.]]

Amphibia are [[predator]]s. They mostly eat live [[invertebrate]]s and animals that do not move too quickly. These include [[caterpillar]]s, earthworms, [[crayfish]], [[water beetle]]s, [[snail]]s and [[dragon fly]] larvae.<ref name=Wells>Wells, Kentwood David 2007. The ecology & behavior of amphibians. University of Chicago Press, {{ISBN|0226893340}}</ref><sup>p667</sup> Many amphibians use their sticky tongues to catch their [[prey]]. They swallow the animal whole, but may chew it just a bit for it to go down their throats. The [[Ranidae]] family and the [[Ceratophrys]] genus eat almost anything they can fit into their mouths.<ref name=Wells/><sup>p668</sup> These include [[rodent]]s, [[bird]]s, [[duck]]lings, small [[fish]] and small mammals.<ref name="americanbullfrog">{{cite web |url=http://www.shastaherps.org/herps/AmericanBullfrog |title=American Bullfrog |work=Shastaherps.org |accessdate=11 July 2012 }}{{Dead link|date=January 2021 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Most frogs are [[cannibalism|cannibalistic]], and may eat each other if food is nowhere to be found. Some amphibians may even eat their own tadpoles and eggs if there is no food for them.<ref name=Lanoo>Lannoo, Michael 2005. Amphibian declines: the conservation status Of United States species. University of California Press, 543. {{ISBN|978-0-520-23592-2}}</ref> 
 
=== Feeding in captivity ===
In [[Captivity (animal)|captivity]], pet frogs will be given [[cricket]]s, [[worm]]s, small fish, rodents and [[fruit flies]].<ref name=Starosta>Starosta, Paul & Moncuit, Teddy 2006. ''Frogs and other amphibians''. ACC Distribution, 122. {{ISBN|978-1-905377-05-3}}</ref> Adult amphibians can help [[wikt:decrease|decrease]] the [[mosquito]] [[population]] by eating most of their [[larvae]].<ref name=Purser>Purser, Phillip 2006. ''Tadpole care''. TFH Publications, 34. {{ISBN|978-0-7938-1035-2}}</ref>

Caecilians eat earthworms, [[termite]]s and beetle larvae, and also small [[lizard]]s.<ref name=Campbell>Campbell, Jonathan A. 1999. ''Amphibians and reptiles of Northern Guatemala, the Yucatán, and Belize''. University of Oklahoma Press, {{ISBN|0806130660}}</ref><sup>p31</sup> Caecilians rely on their smell to find food. They like to eat [[earthworm]]s and will find them by picking up their [[Signal transduction|chemical signals]]. Salamanders and newts are fed a lot of different types of worms. These include [[Lumbriculus variegatus|blood worms]] and earthworms. They can eat small fish such as [[goldfish]], [[fathead minnow]]s and [[guppy|guppies]]. Salamanders also eat crickets and [[rat|pinkies]], which are baby rats.<ref name=Wells/><sup>p771</sup>

== Conservation ==
[[Image:Bufo periglenes1.jpg|thumb|right|The [[golden toad]] of [[Monteverde]], [[Costa Rica]] was last seen in 1989]]

The amphibian population have been decreasing from all locations in the world.<ref name="decline">{{cite journal |last1=McCallum |first1=M.L. |year=2007 |title=Amphibian decline or extinction? Current declines dwarf background extinction rate |journal=Journal of Herpetology |volume=41 |issue=3 |pages=483–491 |doi=10.1670/0022-1511(2007)41[483:ADOECD]2.0.CO;2 |s2cid=30162903 |url=https://www.herpconbio.org/~herpconb/McCallum/amphibian%20extinctions.pdf |access-date=2012-07-22 |archive-date=2008-12-17 |archive-url=https://web.archive.org/web/20081217133741/https://www.herpconbio.org/~herpconb/McCallum/amphibian%20extinctions.pdf |url-status=dead }}</ref> Scientists have said that the declining of amphibians is one of the most [[wikt:critical|critical]] threats to global [[biodiversity]].<ref name="decline"/> A number of causes are believed to be involved. These include [[habitat destruction]], [[over-exploitation]], [[pollution]], introduced species, [[climate change]], destruction of the [[ozone layer]], and diseases like [[chytridiomycosis]]. [[Ultraviolet radiation]] damages the skin, eyes and eggs of amphibians. However, the declines of amphibian population are still not understood.<ref>{{cite web |url=http://www.amphibians.org/ |title=Amphibian Specialist Group |accessdate=2012-03-30}}</ref>

The Amphibian Conservation Action Plan (ACAP) have released a [[global strategy]] to help the amphibian population. It was developed by over 80 leading experts.<ref name=AmphibianArk>{{cite web |url=http://www.iucn.org/about/union/secretariat/offices/asia/regional_activities/asian_amphibian_crisis/taking_action/amphibian_conservation_action_plan/ |title=Amphibian Conservation Action Plan |work=IUCN |accessdate=2012-03-30 |archive-date=2012-04-27 |archive-url=https://web.archive.org/web/20120427134336/http://www.iucn.org/about/union/secretariat/offices/asia/regional_activities/asian_amphibian_crisis/taking_action/amphibian_conservation_action_plan/ |url-status=dead }}</ref> The [[International Union for the Conservation of Nature|Amphibian Specialist Group of the World Conservation Union]] (IUCN) are working on another global strategy to help amphibian populations.<ref name=AmphibianArk/> The [[Amphibian Ark]] (AA) is an [[organization]] that was created to help the public be aware of the decline in amphibian populations. They have been working with [[zoo]]s and [[aquarium|aquaria]] around the world. They try to encourage them to create a natural habitat for threatened amphibians.<ref name=AmphibianArk/> Another project is the Panama Amphibian Rescue and Conservation Project (PARCP) which are trying to spread awareness about chyridiomycosis. The disease is spreading into eastern [[Panama]] and threatening all amphibians living there.<ref>{{cite web |url=http://amphibianrescue.org/?page_id=91 |title=Panama Amphibian Rescue and Conservation Project |accessdate=2012-03-30 |archive-date=2010-06-14 |archive-url=https://web.archive.org/web/20100614024615/http://amphibianrescue.org/?page_id=91 |url-status=dead }}</ref>

On January 21, 2008, Evolutionarily Distinct and Globally Endangered (EDGE) released a statement to the public.<ref>{{cite web |url=http://www.edgeofexistence.org/ |title=Evolutionarily distinct and globally endangered |accessdate=2012-03-30}}</ref> It was created by Helen Meredith, who identified nature's most endangered species. Meredith explains that 85% of the top 100 endangered amphibians list are receiving little or no conservation attention.

== Human use ==
=== As food ===
[[File:Supermarktfrosch.jpg|right|thumb|alt=Three frogs sitting facing each other in a blue container, with a half-opened net over it|Bullfrogs being sold alive at a supermarket in China.]]
Bullfrog legs are a source of food for Southern United States and the Midwestern United States.<ref>{{Citation|title=The illustrated encyclopedia of North American reptiles and amphibians: an essential guide to reptiles and amphibians of USA, Canada, and Mexico |year=2008 |publisher=MobileReference |isbn= 978-1-60501-459-3}}</ref> People hunt bullfrogs at night near rivers. The bullfrogs' legs are cooked, while their backs are [[fried]].<ref name=Gray>Gray, Susan 2009. ''Bullfrog (animal invaders)''. Cherry Lake Publications. {{ISBN|978-1-60279-327-9}}</ref><sup>p9</sup> In China, bullfrogs are sold alive for eating. However, they are later cooked dead with [[vegetable]]s. In the state of California, people must have a license to catch bullfrogs for food.<ref name=Storer>Storer, Malcolm 2004. ''Experimental approaches to conservation biology''. University of California Press. {{ISBN|978-0-520-24024-7}}</ref><sup>p256</sup> In schools, bullfrogs are [[Dissection|dissected]] in [[biology]] classes. Usually, this is done in [[Education in the United States|grammar school]].<ref name=Glotz>Glotzhaber, Robert 1973. ''The life cycle of a Bullfrog''. Children Press. {{ISBN|978-0-87191-233-6}}</ref><sup>p85</sup> The dissecting is a [[Scientific method|method]] for teaching students the [[anatomy]] of a bullfrog.<ref name=Glotz/><sup>p85</sup> The [[emperor newt]] is hunted in China for food. They are also used there for medicine. Burrowing frogs are able to hold water in their bladder, because of this [[indigenous Australians]] use them to drink water.<ref name=Sal/><sup>p13</sup>

=== As pets ===
Amphibians are also kept as pets.<ref name=Grenard>Grenard, Steve 2007. ''Frogs and toads: your happy healthy pet''. Wiley {{ISBN|0470165103}}</ref><sup>p4</sup> They are kept in [[aquarium]]s or a terrarium. A terrarium is a tank that is [[wikt:decorated|decorated]] with plants and [[soil]] on one side. On the other side, there is water. Most amphibians would need one place for land and another for water.<ref name=Grenard/><sup>p8</sup> Each type of amphibian should have its special needs taken care of. Semi-aquatic amphibians need both land and water divided in the tank. Tropical frogs would need [[mist]] and high [[humidity]] in their terrariums.<ref name=Nelson>Nelson, Robin 2002. Pet frog. Lerner. {{ISBN|0822512718}}</ref><sup>p7</sup> Water for amphibia needs [[chlorine|dechlorination]]. The [[chlorine]] in tap water can kill amphibia. Some amphibians popular [[exotic pet]]s, and are found in [[pet store]]s that sell reptiles.<ref name=Grenard/><sup>p22</sup>

==Related pages==
*[[List of amphibians]]
*[[Frogs as pets]]

== References ==
{{reflist|2}}

== Reference books ==
*{{Citation|title=Amphibians|year=2004|last=Morgan|first=Sally|publisher=Heinemann-Raintree Library|isbn=1410910466}}
*{{Citation|title=Amphibians|year=2006|last=Richardson|first=Adele|publisher=Capstone Press|isbn=0736849416}}
*{{Citation|title=The rise of amphibians: 365 million years of evolution|year=2009|last=Carroll|first=Robert L.|publisher=The Johns Hopkins University Press|isbn=978-0-8018-9140-3}}
*{{Citation|title=The Amphibian class|year=2007|last=Stefoff|first= Rebecca |publisher=Marshall Cavendish|isbn=978-0761426929}}
*{{Citation|title=Patterns of distribution of amphibians: a global perspective|year=1999|last=Duellman|first=William Edward|publisher=JHU Press|isbn=0801861152}}
* {{Citation|title=The ecology and behavior of amphibians |last=Wells |first=Kentwood  |year=2007 |publisher=Rosen Publishing Group |isbn=978-0-226-89334-1}}

== Other websites ==
{{wikispecies|Amphibia}}
{{commonscat|Amphibia}}
* [http://www.amphibians.org/ Amphibian Specialist Group]
* [http://www.puce.edu.ec/zoologia/vertebrados/amphibiawebec/index.html AmphibiaWebEcuador] {{Webarchive|url=https://web.archive.org/web/20101011132720/http://www.puce.edu.ec/zoologia/vertebrados/amphibiawebec/index.html |date=2010-10-11 }}
* [http://www.amphibianark.org/ Amphibian Ark]
* [http://www.amphibiaweb.org/ AmphibiaWeb]
* [http://www.edgeofexistence.org/ EDGE]
* [http://www.globalamphibians.org/ Global Amphibian Assessment] {{Webarchive|url=https://web.archive.org/web/20110412222247/http://www.globalamphibians.org/ |date=2011-04-12 }}
* [http://www.npwrc.usgs.gov/narcam/idguide/index.htm USGS—Online Guide for the Identification of Amphibians in North America north of Mexico]
* [http://www.livingunderworld.org/ General amphibian biology information—Living UnderWorld]
* [http://www.amphibianrescue.org Panama Amphibian Rescue and Conservation Project]
* [http://www.atlantabotanicalgarden.org Atlanta Botanical Garden Amphibian Conservation Program]
* [http://www.froglife.org Froglife (British conservation charity)]
* [https://www.amphibianlife.com/what-are-amphibians/ A guide to Amphibians]

{{vertebrates}}
{{Amphibian}}
{{Frogs}}
{{Toad}}
{{Salamanders}}
{{Newts}}
{{Caecilian}}

[[Category:Amphibians| ]]