Editing Amphibian (section)

== Defence mechanisms ==
[[File:Adult Cane toad.jpg|thumb|alt=Cane toad|[[Cane toad]] (''Rhinella marina'') with poison glands behind the eyes]]

Amphibians have soft bodies with thin skins, and lack claws, defensive armour, or spines. Nevertheless, they have evolved various defence mechanisms to keep themselves alive. The first line of defence in salamanders and frogs is the mucous secretion that they produce. This keeps their skin moist and makes them slippery and difficult to grip. The secretion is often sticky and distasteful or toxic.<ref name="Barthalmus">{{cite journal |author1=Barthalmus, G. T. |author2=Zielinski W. J. |year=1988 |title=''Xenopus'' skin mucus induces oral dyskinesias that promote escape from snakes |journal=Pharmacology Biochemistry and Behavior |volume=30 |issue=4 |pages=957–959 |pmid=3227042 |doi=10.1016/0091-3057(88)90126-8 |s2cid=25434883 }}</ref> Snakes have been observed yawning and gaping when trying to swallow [[African clawed frog]]s (''Xenopus laevis''), which gives the frogs an opportunity to escape.<ref name="Barthalmus" /><ref>{{cite web | url=http://amphibiaweb.org/cgi/amphib_query?where-genus=Xenopus&where-species=laevis | title=Xenopus laevis | author=Crayon, John J | publisher=AmphibiaWeb | access-date=October 8, 2012 | archive-date=October 9, 2014 | archive-url=https://web.archive.org/web/20141009195434/http://amphibiaweb.org/cgi/amphib_query?where-genus=Xenopus&where-species=laevis | url-status=live }}</ref> Caecilians have been little studied in this respect, but the Cayenne caecilian (''Typhlonectes compressicauda'') produces toxic mucus that has killed predatory fish in a feeding experiment in Brazil.<ref>{{cite journal |author=Moodie, G. E. E. |year=1978 |title=Observations on the life history of the caecilian ''Typhlonectes compressicaudus'' (Dumeril and Bibron) in the Amazon basin |journal=Canadian Journal of Zoology |volume=56 |issue=4 |pages=1005–1008 |doi=10.1139/z78-141 |bibcode=1978CaJZ...56.1005M |url=https://www.researchgate.net/publication/237980659 |access-date=November 10, 2016 |archive-date=July 5, 2020 |archive-url=https://web.archive.org/web/20200705144951/https://www.researchgate.net/publication/237980659_Observations_on_life-history_of_caecilian_Typhlonectes_compressicaudus_Dumeril_and_Bibron_in_Amazon_Basin/ |url-status=live }}</ref> In some salamanders, the skin is poisonous. The [[rough-skinned newt]] (''Taricha granulosa'') from North America and other members of its genus contain the neurotoxin [[tetrodotoxin]] (TTX), the most toxic non-protein substance known and almost identical to that produced by [[pufferfish]]. Handling the newts does not cause harm, but ingestion of even the most minute amounts of the skin is deadly. In feeding trials, fish, frogs, reptiles, birds and mammals were all found to be susceptible.<ref>{{cite journal |author= Brodie, Edmund D. Jr. |year=1968 |title=Investigations on the skin toxin of the adult rough-skinned newt, ''Taricha granulosa'' |journal=Copeia |volume=1968 |issue=2 |pages=307–313 |jstor=1441757 |doi= 10.2307/1441757 }}</ref><ref name=Hanifin>{{cite journal |author1=Hanifin, Charles T. |author2=Yotsu-Yamashita, Mari |author3=Yasumoto, Takeshi |author4=Brodie, Edmund D. |author5=Brodie, Edmund D. Jr. |year=1999 |title=Toxicity of dangerous prey: variation of tetrodotoxin levels within and among populations of the newt ''Taricha granulosa'' |journal=Journal of Chemical Ecology |volume=25 |issue=9 |pages=2161–2175 |doi=10.1023/A:1021049125805 |bibcode=1999JCEco..25.2161H |s2cid=543221 |url=https://www.researchgate.net/publication/225869249 |access-date=November 10, 2016 |archive-date=July 5, 2020 |archive-url=https://web.archive.org/web/20200705144956/https://www.researchgate.net/publication/225869249_Toxicity_of_Dangerous_Prey_Variation_of_Tetrodotoxin_Levels_Within_and_Among_Populations_of_the_Newt_Taricha_granulosa/ |url-status=live }}</ref> The only predators with some tolerance to the poison are certain populations of [[Common Garter Snake|common garter snake]] (''Thamnophis sirtalis'').
In locations where both snake and salamander co-exist, the snakes have developed immunity through genetic changes and they feed on the amphibians with impunity.<ref>{{cite journal |author1=Geffeney, Shana L. |author2=Fujimoto, Esther |author3=Brodie, Edmund D. |author4=Brodie, Edmund D. Jr. |author5=Ruben, Peter C. |year=2005 |title=Evolutionary diversification of TTX-resistant sodium channels in a predator–prey interaction |journal=Nature |volume=434 |pages=759–763 |doi=10.1038/nature03444 |issue=7034 |pmid=15815629 |bibcode=2005Natur.434..759G |s2cid=4426708 }}</ref> [[Coevolution]] occurs with the newt increasing its toxic capabilities at the same rate as the snake further develops its immunity.<ref name=Hanifin/> Some frogs and toads are toxic, the main poison glands being at the side of the neck and under the warts on the back. These regions are presented to the attacking animal and their secretions may be foul-tasting or cause various physical or neurological symptoms. Altogether, over 200 toxins have been isolated from the limited number of amphibian species that have been investigated.{{sfn | Stebbins | Cohen | 1995 | p=110 }}

[[File:Salamander-olympus.jpg|thumb|left|alt=Fire salamander|The [[fire salamander]] (''Salamandra salamandra''), a toxic species, wears warning colours.]]
[[File:Schrecklicherpfeilgiftfrosch-01.jpg|thumb|left|Perhaps the most poisonous animal in the world, the [[golden poison frog]] (''Phyllobates terribilis'') is endemic to [[Colombia]].<ref>{{cite journal |last1=Patocka |first1=Jiri |last2=Wulff |first2=Kräuff |last3=Palomeque |first3=MaríaVictoria |year=1999 |title=Dart Poison Frogs and Their Toxins |journal=ASA Newsletter |volume=5 |issue=75 |issn=1057-9419 |url=http://www.asanltr.com/ASANews-99/995frogs.htm |access-date=January 29, 2013 |archive-date=March 23, 2014 |archive-url=https://web.archive.org/web/20140323033500/http://www.asanltr.com/ASANews-99/995frogs.htm |url-status=live }}</ref>]]

Poisonous species often use bright colouring to warn potential predators of their toxicity. These warning colours tend to be red or yellow combined with black, with the [[fire salamander]] (''Salamandra salamandra'') being an example. Once a predator has sampled one of these, it is likely to remember the colouration next time it encounters a similar animal. In some species, such as the [[fire-bellied toad]] (''Bombina spp.''), the warning colouration is on the belly and these animals adopt a defensive pose when attacked, exhibiting their bright colours to the predator. The frog ''[[Allobates zaparo]]'' is not poisonous, but [[Batesian mimicry|mimics]] the appearance of other toxic species in its locality, a strategy that may deceive predators.<ref>{{cite journal |author1=Darst, Catherine R. |author2=Cummings, Molly E. |date=March 9, 2006 |title=Predator learning favours mimicry of a less-toxic model in poison frogs |journal=Nature |volume=440 |pages=208–211 |doi=10.1038/nature04297 |issue=7081 |pmid=16525472 |bibcode=2006Natur.440..208D |doi-access=free }}</ref>

Many amphibians are nocturnal and hide during the day, thereby avoiding diurnal predators that hunt by sight. Other amphibians use [[camouflage]] to avoid being detected. They have various colourings such as mottled browns, greys and olives to blend into the background. Some salamanders adopt defensive poses when faced by a potential predator such as the North American [[northern short-tailed shrew]] (''Blarina brevicauda''). Their bodies writhe and they raise and lash their tails which makes it difficult for the predator to avoid contact with their poison-producing granular glands.<ref>{{cite journal |author1=Brodie, Edmund D. Jr. |author2=Nowak, Robert T. |author3=Harvey, William R. |year=1979 |title=Antipredator secretions and behavior of selected salamanders against shrews |journal=Copeia |volume=1979 |issue=2 |pages=270–274 |jstor=1443413 |doi=10.2307/1443413 }}</ref> A few salamanders will autotomise their tails when attacked, sacrificing this part of their anatomy to enable them to escape. The tail may have a constriction at its base to allow it to be easily detached. The tail is regenerated later, but the energy cost to the animal of replacing it is significant.<ref name="Beneski" />
Some frogs and toads inflate themselves to make themselves look large and fierce, and some spadefoot toads (''[[Pelobates]] spp'') scream and leap towards the attacker.<ref name="Collins" /> Giant salamanders of the genus ''[[Andrias]]'', as well as [[Ceratophryinae|Ceratophrine]] and ''[[Pyxicephalus]]'' frogs possess sharp teeth and are capable of drawing blood with a defensive bite. The [[blackbelly salamander]] (''Desmognathus quadramaculatus'') can bite an attacking common garter snake (''Thamnophis sirtalis'') two or three times its size on the head and often manages to escape.<ref>{{cite journal |author=Brodie, E. D. Jr. |year=1978 |title=Biting and vocalisation as antipredator mechanisms in terrestrial salamanders |journal=Copeia |volume=1978 |issue=1 |pages=127–129 |jstor=1443832 |doi=10.2307/1443832 }}</ref>