Editing Hellbender (section)

==Description==
''Cryptobranchus alleganiensis'' has a flat body and head, with beady dorsal [[eye]]s and slimy skin. Like most salamanders, it has short legs with four toes on the front legs and five on its back limbs, and its tail is keeled for propulsion. Its tail is shaped like a rudder, but it is rarely used for swimming; these salamanders instead use pads on their toes to grip rocks and walk up and down streams instead of swimming.<ref name="Humphries-2005">{{cite journal | last1=Humphries | first1=W. Jeffrey | last2=Pauley | first2=Thomas K.  | issn=0003-0031 | year=2005  | title=Life History of the Hellbender, ''Cryptobranchus alleganiensis'', in a West Virginia Stream | journal=The American Midland Naturalist | volume=154 | issue=1 | pages=135-142 | doi=10.1674/0003-0031(2005)154[0135:LHOTHC]2.0.CO;2}}</ref> The hellbender has working lungs, but gill slits are often retained, although only immature specimens have true gills; the hellbender absorbs oxygen from the water through capillaries of its side frills.<ref name=fws1/> The frills run from their neck down to the base of their tail on each side of their body. The frills’ function is to increase the surface area of the hellbender and to help the hellbender breathe.<ref>{{Cite journal |last1=Pugh |first1=M. W. |last2=Groves |first2=J.D. |last3=Williams |first3=L.A. |last4=Gangloff |first4=M.M. |date=2013 |title=A previously undocumented locality of eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) in the Elk River, Carter County, TN. |journal=Southeastern Naturalist |volume=12 |issue=1 |pages=137–142|doi=10.1656/058.012.0111 }}</ref> Only occasionally leaving the water, the hellbender makes little use of these lungs and the juveniles lose their external gills after around 18 months or about {{cvt|125|mm}} in length.<ref name="ReferenceA">{{Cite journal |last1=Unger |first1=Shem D. |last2=Jr |first2=Olin E. Rhodes |last3=Sutton |first3=Trent M. |last4=Williams |first4=Rod N. |date=2013-10-18 |title=Population Genetics of the Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis) across Multiple Spatial Scales |journal=PLOS ONE |language=en |volume=8 |issue=10 |pages=e74180 |doi=10.1371/journal.pone.0074180 |doi-access=free |issn=1932-6203 |pmc=3800131 |pmid=24204565|bibcode=2013PLoSO...874180U }}</ref><ref>Hellbender salamander. The Nature Conservancy. (n.d.). Retrieved April 20, 2022, from https://www.nature.org/en-us/get-involved/how-to-help/animals-we-protect/hellbender-salamander/</ref> Hellbenders use their lungs for buoyancy more than breathing.<ref name="Humphries-2005"/> It is blotchy brown or red-brown in color, with a paler underbelly. Hellbenders can also be described as having a gray, or yellowish-brown, to even black coloration.<ref>{{Cite book |last1=Powell |first1=Robert |title=Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America |last2=Conant |first2=Roger |last3=Collins |first3=Joseph T. |publisher=HarperCollins |year=2016 |edition=4th}}</ref>

Both males and females grow to an adult length of {{convert|24|to|40|cm|in|abbr=on}} from snout to [[cloaca|vent]], with a total length of {{convert|30|to|74|cm|in|abbr=on}}, making them the fourth-largest aquatic salamander species in the world (after the [[South China giant salamander]], the [[Chinese giant salamander]] and the [[Japanese giant salamander]], respectively) and the largest amphibian in North America, although this length is rivaled by the [[reticulated siren]] of the southeastern [[United States]] (although the siren is much leaner in build).<ref>{{Cite web|url=https://news.mongabay.com/2019/09/chinese-giant-salamander-new-species-largest-amphibian/|title = Newly described Chinese giant salamander may be world's largest amphibian|date = 17 September 2019}}</ref><ref name=amphibiaweb1/> While males and females grow at similar rates, the females tend to live longer and therefore grow larger.<ref>{{Cite journal |last1=Taber |first1=Charles A. |last2=Wilkinson |first2=R. F. |last3=Topping |first3=Milton S. |date=1975 |title=Age and Growth of Hellbenders in the Niangua River, Missouri |url=https://www.jstor.org/stable/1443315 |journal=Copeia |volume=1975 |issue=4 |pages=633–639 |doi=10.2307/1443315 |jstor=1443315 |issn=0045-8511|url-access=subscription }}</ref> Adults weigh {{convert|1.5|to|2.5|kg|lb|abbr=on}}, making them the fifth heaviest living amphibian in the world after their South China, Chinese and Japanese cousins and the [[goliath frog]], while the largest [[cane toad]]s may also weigh as much as a hellbender. Hellbenders reach sexual maturity at about five years of age, and may live 30 years in captivity.<ref name=fws1>Mayasich, J.; Grandmaison, D.; Phillips, C. (June 2003) [http://www.fws.gov/midwest/es/soc/amphibians/eahe-sa.pdf Eastern Hellbender Status Assessment Report]</ref>

The hellbender has a few characteristics that make it distinguishable from other native salamanders, including a gigantic, dorsoventrally flattened body with thick folds travelling down the sides, a single open [[gill slit]] on each side, and hind feet with five toes each.<ref name=cryptobranchus1263>{{cite journal|last=Guimond |first=R.W.|author2=Hutchison, V.H.|title=Aquatic Respiration: An Unusual Strategy in the Hellbender ''Cryptobranchus alleganiensis alleganiensis'' (Daudin)|journal=Science|date=21 December 1973|volume=182 |issue=4118|pages=1263–1265|doi=10.1126/science.182.4118.1263|pmid=17811319|bibcode=1973Sci...182.1263G|s2cid=43586570}}</ref><ref>{{cite journal |last=Gehlbach |first=Frederick R. |title=Comments on the Study of Ohio Salamanders with Key to Their Identification |journal=Journal of the Ohio Herpetological Society |year=1960 |volume=2 |issue=3 |pages=40–45}}</ref> Easily distinguished from most other endemic salamander species simply by their size, hellbenders average up to {{cvt|60|cm|ft}} in length; the only species requiring further distinction (due to an overlap in distribution and size range) is the [[common mudpuppy]] (''Necturus maculosus'').<ref name=cryptobranchus2>{{cite journal|last=Crowhurst|first=R.S.|author2=Faries, K.M.|author3=Collantes, J. |author4=Briggler, J.T.|author5=Koppelman, J.B.|author6=Eggert, L.S. |title=Genetic relationships of hellbenders in the Ozark highlands of Missouri and conservation implications for the Ozark subspecies (''Cryptobranchus alleganiensis bishopi'')|journal=Conservation Genetics|date=28 December 2010|volume=12 |issue=3|pages=637–646|doi=10.1007/s10592-010-0170-0|s2cid=24257951}}</ref><ref name=amphibiaweb1>[http://amphibiaweb.org/cgi-bin/amphib_query?query_src=aw_lists_genera_&table=amphib&where-genus=Cryptobranchus&where-species=alleganiensis ''Cryptobranchus alleganiensis''] AmphibiaWeb: Information on amphibian biology and conservation. [web application]. 2012. Berkeley, California: AmphibiaWeb. Available: http://amphibiaweb.org/. (Accessed: 15 November 2012).</ref> This demarcation can be made by noting the presence of external gills in the mudpuppy, which are lacking in the hellbender, as well as the presence of four toes on each hind foot of the mudpuppy (in contrast with the hellbender's five).<ref name=cryptobranchus1263/> Furthermore, the average size of ''C.&nbsp;a.&nbsp;alleganiensis'' has been reported to be {{cvt|45–60|cm}} (with some reported as reaching up to {{cvt|74|cm}}), while ''N.&nbsp;m.&nbsp;maculosus'' has a reported average size of {{convert|28|to|40|cm|in|abbr=on}} in length, which means that hellbender adults will still generally be notably larger than even the biggest mudpuppies.<ref name=cryptobranchus2/><ref>{{cite book|last=Lanza|first=B.|author2=Vanni, S.|author3=Nistri, A.  |title=Encyclopedia of Reptiles & Amphibians|year=1998|publisher=Academic Press |location=San Diego, CA |isbn=978-0121785604|edition=2nd|editor1=Cogger, Harold G.|editor-link=Harold Cogger|editor2=Zweifel, Richard G.|editor2-link=Richard G. Zweifel|pages=70–74}}</ref><ref name=phylogeography1235>{{cite journal|last=Sabatino|first=Stephen J.|author2=Routman, Eric J. |title=Phylogeography and conservation genetics of the hellbender salamander (''Cryptobranchus alleganiensis'') |journal=Conservation Genetics|date=October 2009|volume=10|issue=5|pages=1235–1246 |doi=10.1007/s10592-008-9655-5|bibcode=2009ConG...10.1235S |s2cid=12703020}}</ref>

{{Gallery|mode=packed
|Hellbender Cryptobranchus alleganiensis.jpg|The small eyes and loose skin are characteristic of hellbenders.
|Cryptobranchus alleganiensis 2.jpg|Skeleton and model
|Hellbender Cryptobranchus.jpg|In captivity
}}