hellbender

The origin of the name "hellbender" is unclear. The Missouri Department of Conservation says:{{cite report |last1=Johnson |first1=Tom R. |last2=Briggler |first2=Jeff |year=2004 |title=The Hellbender |series=Herpetology Lab |place=Jefferson City, MO |publisher=The Conservation Commission of the State of Missouri |url=https://ag.purdue.edu/fnr/discover/HerpetologyLab/Documents/Johnson_TheHellbender.pdf |url-status=dead |access-date=16 May 2013 |archive-url=https://web.archive.org/web/20170503141120/https://ag.purdue.edu/fnr/discover/HerpetologyLab/Documents/Johnson_TheHellbender.pdf |archive-date=3 May 2017 }}

The name 'hellbender' probably comes from the animal's odd look. One theory claims the hellbender was named by settlers who thought "it was a creature from hell where it's bent on returning." Another rendition says the undulating skin of a hellbender reminded observers of "horrible tortures of the infernal regions." In reality, it's a harmless aquatic salamander.

In a study conducted in Indiana, informing the public about the rarity and locality of the hellbender resulted in more positive attitudes toward this species than were previously held.{{cite journal |first1=A. |last1=Reimer |first2=A. |last2=Mase |first3=K. |last3=Mulvaney |first4=N. |last4=Mullendore |first5=R. |last5=Perry-Hill |first6=L. |last6=Prokopy |publication-date=June 2014 |orig-date=22 October 2013 |title=The impact of information and familiarity on public attitudes toward the eastern hellbender |journal=Animal Conservation |volume=17 |issue=3 |pages=235–243 |doi=10.1111/acv.12085 |bibcode=2014AnCon..17..235R |url=https://ag.purdue.edu/department/extension/hellbender/_docs/reimer-hellbender-familiarity-ada.pdf |via=ag.purdue.edu }} Other vernacular names include snot otter,{{cite news |last=Sofia |first=Madeline K. |date=14 September 2017 |title=Snot otters get a second chance in Ohio |publisher=National Public Radio |quote=Snot otter; lasagna lizard: Pick your favorite nickname for the Eastern hellbender salamander. |url=https://www.npr.org/2017/09/14/545796084/video-snot-otters-get-a-second-chance-in-ohio }} lasagna lizard, devil dog, mud-devil, mud dog, water dog, grampus,{{cite dictionary |title=grampus |date=Spring 2020 |dictionary=Dictionary of American Regional English |publisher=University of Wisconsin |place=Madison, WI |id=Quarterly update 20 |url=https://dare.wisc.edu/words/quarterly-updates/quarterly-update-20-spring-2020-2/grampus/ |via=dare.wisc.edu }} Allegheny alligator, and leverian water newt.{{cite book |last1=Nickerson |first1=Max Allen |last2=Mays |first2=Charles Edwin |year=1973 |title=The Hellbenders: North American "giant salamanders" |publisher=Milwaukee Public Museum |series=Publications in Biology and Geology |volume=1 }}

The generic name, Cryptobranchus, is derived from the Ancient Greek {{Transliteration|grc|kryptos}} (hidden) and {{Transliteration|grc|branchion}} (gill).{{cite web |last=Miller |first=Jessica J. |title=Cryptobranchus alleganiensis |series=Caudata database |publisher=livingunderworld.org |website=amphibiainfo.com |url=http://www.amphibiainfo.com/caudata/database/cryptobranchidae/cryptobranchus/alleganiensis/ |url-status=usurped |access-date=12 November 2012 |archive-url=https://web.archive.org/web/20140111053400/http://www.amphibiainfo.com/caudata/database/cryptobranchidae/cryptobranchus/alleganiensis/ |archive-date=11 January 2014 }} The subspecies name bishopi honors the American herpetologist Sherman C. Bishop.{{cite book |last=Beltz |first=Ellin |year=2006 |chapter=Bishop, Sherman Chauncey |title=Scientific and Common Names of the Reptiles and Amphibians of North America — Explained |chapter-url=http://ebeltz.net/herps/biogappx.html }}{{cite dictionary |last1=Beolens |first1=Bo |last2=Watkins |first2=Michael |last3=Grayson |first3=Michael |year=2013 |title=Cryptobranchus alleganiensis bishopi |dictionary=The Eponym Dictionary of Amphibians |location=Exeter, UK |publisher=Pelagic Publishing Ltd. |isbn=978-1-907807-41-1 |page=23}}

Cryptobranchus alleganiensis has a flat body and head, with beady dorsal eyes 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.{{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}} 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. 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.{{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 }} 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.{{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 }}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/ Hellbenders use their lungs for buoyancy more than breathing. 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.{{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}}

Both males and females grow to an adult length of {{convert|24|to|40|cm|in|abbr=on}} from snout to 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).{{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}} While males and females grow at similar rates, the females tend to live longer and therefore grow larger.{{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 }} 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 toads 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.Mayasich, J.; Grandmaison, D.; Phillips, C. (June 2003) [http://www.fws.gov/midwest/es/soc/amphibians/eahe-sa.pdf Eastern Hellbender Status Assessment Report]

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.{{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}}{{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}} 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).{{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}}[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). 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). Furthermore, the average size of C. a. alleganiensis has been reported to be {{cvt|45–60|cm}} (with some reported as reaching up to {{cvt|74|cm}}), while N. m. 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.{{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}}{{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}}

{{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

}}

The genus Cryptobranchus has historically been considered to contain only one species, C. alleganiensis, with two subspecies, C. a. alleganiensis and C. a. bishopi. A recent decline in population size of the Ozark subspecies C. a. bishopi has led to further research into populations of this subspecies, including genetic analysis to determine the best method for conservation.

Crowhurst et al., for instance, found that the "Ozark subspecies" denomination is insufficient for describing genetic (and therefore evolutionary) divergence within the genus Cryptobranchus in the Ozark region. They found three equally divergent genetic units within the genus: C. a. alleganiensis, and two distinct eastern and western populations of C. a. bishopi. These three groups were shown to be isolated, and are considered to most likely be "diverging on different evolutionary paths".

Hellbenders are present in a number of Eastern US states, from southern New York to northern Georgia,{{cite journal|last=Peterson|first=C.L |author2=Metter, D.E.|author3=Miller, B.T.|author4=Wilkinson, R.F.|author5=Topping, M.S.|title=Demography of the Hellbender Cryptobranchus alleganiensis in the Ozarks|journal=American Midland Naturalist|date=April 1988|volume=199|issue=2|pages=291–303|jstor=2425812|doi=10.2307/2425812|s2cid=85842376 }} including parts of Ohio, Pennsylvania, Maryland, West Virginia, Virginia, Kentucky, Illinois, Indiana, Tennessee, North Carolina, South Carolina, Alabama, Mississippi, Arkansas, Missouri, and extending into Oklahoma and Kansas. However, only one documented sighting has been recorded in South Carolina. The subspecies (or species, depending on the source) C. a. bishopi is confined to the Ozarks of northern Arkansas and southern Missouri, while C. a. alleganiensis is found in the rest of these states.{{cite journal |last=Williams |first=R.D. |author2=Gates, J.T. |author3=Hocutt, C.H |author4=Taylor, G.J. |title=The Hellbender: A Nongame Species in Need of Management |journal=Wildlife Society Bulletin |volume=9 |issue=2 |year=1981 |pages=94–100 |jstor=3781577}}

Some hellbender populations—namely a few in Missouri, Pennsylvania, and Tennessee—have historically been noted to be quite abundant, but several man-made threats have converged on the species such that it has seen a serious population decline throughout its range.{{cite journal |last1=Albanese |first1=Brett |last2=Jensen |first2=John B. |last3=Unger |first3=Shem D. |title='Occurrence of the Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis) in the Coosawattee River System (Mobile River Basin), Georgia |journal=Southeastern Naturalist |date=2011 |volume=10 |issue=1 |pages=181–184|doi=10.1656/058.010.0116|s2cid=84971915 }} In Missouri, it is estimated that the populations have declined by 77% since the 1980s.Catherine M. Bodinof, Jeffrey T. Briggler, Randall E. Junge, Tony Mong, Jeff Beringer, Mark D. Wanner, Chawna D. Schuette, Jeff Ettling, Joshua J. Millspaugh; Survival and Body Condition of Captive-Reared Juvenile Ozark Hellbenders (Cryptobranchus alleganiensis bishopi) Following Translocation to the Wild. Copeia 30 March 2012; 2012 (1): 150–159. doi: https://doi.org/10.1643/CH-11-024 Hellbender populations were listed in 1981 as already extirpated or endangered in Illinois, Indiana, Iowa, and Maryland, decreasing in Arkansas and Kentucky, and generally threatened as a species throughout their range by various human activities and developments.

Hellbenders are found in clear, clean water, and their presence is an indicator that the water is of good quality.Keitzer, S. C., Pauley, T. K., & Burcher, C. L. (2013). Stream characteristics associated with site occupancy by the eastern hellbender, Cryptobranchus alleganiensis alleganiensis, in southern West Virginia. Northeastern Naturalist, 20(4), 666–677. The hellbender salamander, considered a "habitat specialist", has adapted to fill a specific niche within a very specific environment, and is labeled as such "because its success is dependent on a constancy of dissolved oxygen, temperature and flow found in swift water areas", which in turn limits it to a narrow spectrum of stream/river choices. As a result of this specialization, hellbenders are generally found in areas with large, irregularly shaped, and intermittent rocks and swiftly moving water, while they tend to avoid wider, slow-moving waters with muddy banks and/or slab rock bottoms. This specialization likely contributed to the decline in their populations, as collectors could easily identify their specific habitats. One collector noted, at one time, "one could find a specimen under almost every suitable rock", but after years of collecting, the population had declined significantly.{{cite journal |last=Swanson |first=P.L. |title=Notes on the Amphibians of Venango County, Pennsylvania |journal=American Midland Naturalist |date=September 1948 |volume=40 |issue=2 |pages=362–371 |doi=10.2307/2421606|jstor=2421606 |s2cid=87410957 }} The same collector noted, he "never found two specimens under the same rock", corroborating the account given by other researchers that hellbenders are generally solitary; they are thought to gather only during the mating season.{{cite journal |last1=Humphries |first1=W.J. |last2=Pauley |first2=T.K. |title=Seasonal Changes in Nocturnal Activity of the Hellbender, Cryptobranchus alleganiensis, in West Virginia |journal=Journal of Herpetology |date=December 2000 |volume=34 |issue=4 |pages=604–607 |jstor=1565279 |doi=10.2307/1565279}} If rocks are lacking, hellbenders have been known to use holes in stream banks as habitat. On average, their home range is estimated to be 198 square meters as of 2005.W. JEFFREY HUMPHRIES and THOMAS K. PAULEY "Life History of the Hellbender, Cryptobranchus alleganiensis, in a West Virginia Stream," The American Midland Naturalist 154(1), 135–142, (1 July 2005). https://doi.org/10.1674/0003-0031(2005)154[0135:LHOTHC]2.0.CO;2 The ideal habitat for a hellbender has a large amount of gravel, low pH, cool water temperatures, and low specific conductivity. The large amounts of gravel enable the hellbender to hide, cool water temperatures allow for more efficient cutaneous gas exchange, and low specific conductivity may indicate an undisturbed stream. Hellbender communities may be more concentrated in undisturbed areas.

Both subspecies, C. a. alleganiensis and C. a. bishopi undergo a metamorphosis after around a year and a half of life. At this point, when they are roughly {{Cvt|13.5|cm}} long, they lose the gills present during their larval stage. Until then, they are easily confused with mudpuppies, and can be differentiated often only through toe number. After this metamorphosis, hellbenders must be able to absorb oxygen through the folds in their skin, which is largely behind the need for fast-moving, oxygenated water. If a hellbender ends up in an area of slow-moving water, not enough of it will pass over its skin in a given time, making it difficult to garner enough oxygen to support necessary respiratory functions. A below-favorable oxygen content can make life equally difficult.

Hellbenders are preyed upon by diverse predators, including various fish and reptiles (including both snakes and turtles). Particularly, largemouth bass is a predator that can consume a hellbender 1–3 years old.{{Cite journal |last1=Kenison |first1=Erin K. |last2=Williams |first2=Rod N. |date=2018 |title=Training for Translocation: Predator Conditioning Induces Behavioral Plasticity and Physiological Changes in Captive Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis) (Cryptobranchidae, Amphibia) |journal=Diversity |language=en |volume=10 |issue=1 |pages=13 |doi=10.3390/d10010013 |doi-access=free |bibcode=2018Diver..10...13K |issn=1424-2818}} Cannibalism of eggs is also considered a common occurrence. One study found that in areas with increased deforestation, the likelihood of filial cannibalism increases.Hopkins, William A., et al. "Filial cannibalism leads to chronic nest failure of eastern hellbender salamanders (Cryptobranchus alleganienesis)." The American Naturalist 202.1 (2023).

In another study by Kenison & Wilson (2018), researchers found that young, captive hellbenders showed altered behavior in response to predatory fish nearby. Because of their altered behavior, it was observed and concluded that hellbenders are capable of detecting kairomones, which are chemical cues emitted by predatory species. This suggests that hellbenders can recognize kairomones as stressful stimuli and identify potential predators.

Once a hellbender finds a favorable location, it generally does not stray too far from it—except occasionally for breeding and hunting—and will protect it from other hellbenders both in and out of the breeding season. While the range of two hellbenders may overlap, they are noted as rarely being present in the overlapping area when the other salamander is in the area. The species is at least somewhat nocturnal, with peak activity being reported by one source as occurring around "two hours after dark" and again at dawn (although the dawn peak was recorded in the lab and could be misleading as a result). Nocturnal activity has been found to be most prevalent in early summer, perhaps coinciding with highest water depths. Adult hellbenders can live up to 25–30 years.Kaunert, M. D., Brown, R. K., Spear, S., Johantgen, P. B., & Popescu, V. D. (2023). Restoring eastern hellbender (Cryptobranchus a. alleganiensis) populations through translocation of headstarted individuals. Population Ecology.

C. alleganiensis feeds primarily on crayfish and small fish, but also insects, worms, molluscs, tadpoles and smaller salamanders.{{Cite web |last=Pike |first=Zeb |title=Cryptobranchus alleganiensis (Hellbender) |url=https://animaldiversity.org/accounts/Cryptobranchus_alleganiensis/ |access-date=2025-04-09 |website=Animal Diversity Web |language=en}}{{Cite web |title=AmphibiaWeb - Cryptobranchus alleganiensis |url=https://amphibiaweb.org/species/3861 |access-date=2025-04-09 |website=amphibiaweb.org |language=en}} A study conducted in 2017 found that larval hellbenders eat mayfly and caddisfly nymphs.Kirsten A. Hecht, Max A. Nickerson, Phillip B. Colclough "Hellbenders (Cryptobranchus alleganiensis) May Exhibit an Ontogenetic Dietary Shift," Southeastern Naturalist, 16(2), 157–162, (1 June 2017) One report, written by a commercial collector in the 1940s, noted a trend of more crayfish predation in the summer during times of higher prey activity, whereas fish made up a larger part of the winter diet, when crayfish are less active. There seems to be a specific temperature range in which hellbenders feed, as well: between {{convert|45|and|80|F|C|abbr=on}}. Cannibalism—mainly on eggs—has been known to occur within hellbender populations. One researcher claimed perhaps density is maintained, and density dependence in turn created, in part by intraspecific predation. When feeding on large prey items relative to themselves, it has been found that they use suction feeding.{{Cite journal |last1=Deban |first1=Stephen M. |last2=O’Reilly |first2=James C. |date=2005 |title=The ontogeny of feeding kinematics in a giant salamander Cryptobranchus alleganiensis: Does current function or phylogenetic relatedness predict the scaling patterns of movement? |url=https://doi.org/10.1016/j.zool.2005.03.006 |journal=Zoology |volume=108 |issue=2 |pages=155–167 |doi=10.1016/j.zool.2005.03.006 |pmid=16351963 |bibcode=2005Zool..108..155D |issn=0944-2006|url-access=subscription }}

The hellbenders' breeding season begins in late August or early- to mid-September and can continue as late as the end of November, depending on region. They exhibit no sexual dimorphism, except during the fall mating season, when males have a bulging ring around their cloacal glands. Unlike most salamanders, the hellbender performs external fertilization. Before mating, each male excavates a brood site, a saucer-shaped depression under a rock or log, with its entrance positioned out of the direct current, usually pointing downstream. The male remains in the brood site awaiting a female. Males will combat for nest sites, often biting to defend the nest rock of their choice.{{Cite journal |last=Unger |first=Shem |last2=Catherine M. Bodinof Jachowski |last3=Diaz |first3=Lauren |last4=Williams |first4=Lori A. |date=November 2020 |title=Shelter Guarding Behavior of the Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis) in North Carolina Streams |url=https://bioone.org/journals/southeastern-naturalist/volume-19/issue-4/058.019.0411/Shelter-Guarding-Behavior-of-the-Eastern-Hellbender-Cryptobranchus-alleganiensis-alleganiensis/10.1656/058.019.0411.short |journal=Southeastern Naturalist |language=en |volume=19 |issue=4 |doi=10.1656/058.019.0411.short |issn=1528-7092 |archive-url=http://web.archive.org/web/20240905042428/https://bioone.org/journals/southeastern-naturalist/volume-19/issue-4/058.019.0411/Shelter-Guarding-Behavior-of-the-Eastern-Hellbender-Cryptobranchus-alleganiensis-alleganiensis/10.1656/058.019.0411.short |archive-date=2024-09-05}} When a female approaches, the male guides or drives her into his burrow and prevents her from leaving until she oviposits.

Female hellbenders lay 150–200 eggs over a two- to three-day period; the eggs are {{Cvt|18-20|mm}} in diameter, connected by five to ten cords. As the female lays eggs, the male positions himself alongside or slightly above them, spraying the eggs with sperm while swaying his tail and moving his hind limbs, which disperses the sperm uniformly. The male often tempts other females to lay eggs in his nest, and as many as 1,946{{cite book|title=Encyclopedia of Reptiles and Amphibians|author=Chris Mattison|year=2005|page=23|publisher=The Brown Reference Group}} eggs have been counted in a single nest. Males also exhibit mate and shelter guarding. Mortality rate is high for hellbender eggs. Studies have found that until the female successfully reproduces, the male hellbender will guard her in his territory until the reproduction is complete. Cannibalism, however, leads to a much lower number of eggs in hellbender nests than would be predicted by egg counts. Adult males are more likely to cannibalize their own offspring in degraded sites with limited food availability.{{Cite journal |last1=Hopkins |first1=William A. |last2=Case |first2=Brian F. |last3=Groffen |first3=Jordy |last4=Brooks |first4=George C. |last5=Bodinof Jachowski |first5=Catherine M. |last6=Button |first6=Sky T. |last7=Hallagan |first7=John J. |last8=O’Brien |first8=Rebecca S. M. |last9=Kindsvater |first9=Holly K. |date=2023-07-01 |title=Filial Cannibalism Leads to Chronic Nest Failure of Eastern Hellbender Salamanders ( Cryptobranchus alleganiensis ) |url=https://www.journals.uchicago.edu/doi/10.1086/724819 |journal=The American Naturalist |language=en |volume=202 |issue=1 |pages=92–106 |doi=10.1086/724819 |pmid=37384763 |bibcode=2023ANat..202...92H |issn=0003-0147|url-access=subscription }}

After oviposition, the male drives the female away from the nest and guards the eggs. Incubating males rock back and forth and undulate their lateral skin folds, which circulates the water, increasing oxygen supply to both eggs and adult. Incubation lasts from 45 to 75 days, depending on region. Males are known to show solitary parental care for the eggs and larvae for at least 7–8 months.{{Cite journal |last1=Galligan |first1=Thomas M. |last2=Helm |first2=Richard F. |last3=Case |first3=Brian F. |last4=Bodinof Jachowski |first4=Catherine M. |last5=Frazier |first5=Clara L. |last6=Alaasam |first6=Valentina |last7=Hopkins |first7=William A. |date=2021-11-01 |title=Pre-breeding androgen and glucocorticoid profiles in the eastern hellbender salamander (Cryptobranchus alleganiensis alleganiensis) |journal=General and Comparative Endocrinology |volume=313 |pages=113899 |doi=10.1016/j.ygcen.2021.113899 |pmid=34499909 |issn=0016-6480|doi-access=free }}

Hatchling hellbenders are {{Cvt|25-33|mm}} long, have a yolk sac as a source of energy for the first few months of life, and lack functional limbs.

Hellbenders are superbly adapted to the shallow, fast-flowing, rocky streams in which they live. Their flattened shape offers little resistance to the flowing water, allowing them to work their way upstream and also to crawl into narrow spaces under rocks. The wrinkles and folds along their skin are used to expand surface area for cutaneous respiration.{{Cite web |title=Hellbender Salamander |url=https://www.nature.org/en-us/get-involved/how-to-help/animals-we-protect/hellbender-salamander/ |access-date=2023-01-24 |website=The Nature Conservancy |language=en-US}} Their skin also has a secretion that is important for innate immunity against chytrid activity.{{Cite journal |last1=Hardman |first1=Rebecca H. |last2=Reinert |first2=Laura K. |last3=Irwin |first3=Kelly J. |last4=Oziminski |first4=Kendall |last5=Rollins-Smith |first5=Louise |last6=Miller |first6=Debra L. |date=2023-02-03 |title=Disease state associated with chronic toe lesions in hellbenders may alter anti-chytrid skin defenses |journal=Scientific Reports |language=en |volume=13 |issue=1 |pages=1982 |doi=10.1038/s41598-023-28334-4 |issn=2045-2322 |pmc=9898527 |pmid=36737574|bibcode=2023NatSR..13.1982H }} Although their eyesight is relatively poor, they have light-sensitive cells all over their bodies. Those on their tails are especially finely tuned and may help them position safely under rocks without their tails poking out to give themselves away. They have a good sense of smell and move upstream in search of food such as dead fish, following the trail of scent molecules. Smell is possibly their most important sense when hunting. They also have a lateral line similar to those of fish, with which they can detect vibrations in the water.{{cite book|last=Mattison|first=Chris|title=Encyclopedia of Reptiles and Amphibians|year=2005|publisher=Grange Books|location=Rochester, Kent|isbn=978-1-84013-794-1|page=22|chapter=What is an amphibian?}}

File:Hellbender Salamander.JPG, Washington, D.C.]]

Research throughout the range of the hellbender has shown a dramatic decline in populations in the majority of locations. As of 2022, the species is classified as Vulnerable by the IUCN. Many different anthropogenic sources have contributed to this decline, including the siltation and sedimentation, blocking of dispersal/migration routes, and destruction of riverine habitats created by dams and other development, as well as pollution, disease and overharvesting for commercial and scientific purposes. As many of these detrimental effects have irreversibly damaged hellbender populations, it is important to conserve the remaining populations through protecting habitats and—perhaps in places where the species was once endemic and has been extirpated—by augmenting numbers through reintroduction.

Due to sharp decreases seen in the Ozark subspecies, researchers have been trying to differentiate C. a. alleganiensis and C. a. bishopi into two management units. Indeed, researchers found significant genetic divergence between the two groups, as well as between them and another isolated population of C. a. alleganiensis. This could be reason enough to ensure work is done on both subspecies, as preserving extant genetic diversity is of crucial ecological importance.

The Ozark hellbender has been listed as an endangered species under the Endangered Species Act by the US Fish and Wildlife Service since October 5, 2011. This hellbender subspecies inhabits the White River and Spring River systems in southern Missouri and northern Arkansas, and its population has declined an estimated 75% since the 1980s, with only about 590 individuals remaining in the wild. Degraded water quality, habitat loss resulting from impoundments, ore and gravel mining, sedimentation, and collection for the pet trade are thought to be the main factors resulting in the amphibian's decline.{{cite press release |title=U.S. Fish and Wildlife Service Lists the Ozark Hellbender as Endangered and Moves to Include Hellbenders in Appendix III of CITES |publisher=U. S. Fish and Wildlife Service |date=2011-10-05 |url=http://www.fws.gov/midwest/endangered/amphibians/ozhe/NRFinalListingozhe.html?rid=273 |access-date=16 May 2013}} When chytridiomycosis killed 75% of the St. Louis Zoo's captive hellbender population between March 2006 and April 2007, tests began to be conducted on wild populations. The disease has been detected in all Missouri populations of the Ozark hellbender.{{cite web |title=The Ozark Hellbender – Can We Save It? |url=http://www.fws.gov/midwest/endangered/esday/MOOZHE.html|publisher=U.S. Fish and Wildlife Service |access-date=26 January 2013}} NatureServe treats C. a. alleganiensis as an Imperiled Subspecies, C. a. bishopi as a Critically Imperiled Subspecies, and the species as a whole as Vulnerable.{{cite web |title=NatureServe Explorer 2.0 |url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.101863/Cryptobranchus_alleganiensis_alleganiensis |website=explorer.natureserve.org |access-date=28 March 2022}}{{cite web |title=NatureServe Explorer 2.0 |url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.102421/Cryptobranchus_alleganiensis_bishopi |website=explorer.natureserve.org |access-date=28 March 2022}}{{cite web |title=NatureServe Explorer 2.0 |url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.105670/Cryptobranchus_alleganiensis |website=explorer.natureserve.org |access-date=28 March 2022}}

The Ozark hellbender was successfully bred in captivity for the first time at the St. Louis Zoo, in a joint project with the Missouri Department of Conservation, hatching on November 15, 2011.{{cite web |author=Saint Louis Zoo |url=https://www.sciencedaily.com/releases/2011/12/111201094756.htm |title=World's first captive breeding of Ozark hellbenders |website=ScienceDaily |date=1 December 2011 |access-date=15 November 2012}}

Apart from the Ozark efforts, head-starting programs, in which eggs are collected from the wild and raised in captivity for re-release at a less vulnerable stage, have been initiated in Indiana, New York,{{cite news |last=James |first=Will |url=https://www.wsj.com/articles/SB10001424127887324108204579024753735118762 |title=The Buffalo Zoo's Hellbender Lab |newspaper=Wall Street Journal |date=20 August 2013}} and Ohio.{{cite press release |title=Ohio's Hellbender Population Set Up for Success |url=http://ohiodnr.gov/news/post/ohio-s-hellbender-population-set-up-for-success |date=9 October 2014 |publisher=Ohio Department of Natural Resources |access-date=10 January 2015}}

Members of the Pennsylvania State Senate have voted to approve the eastern hellbender as the official state amphibian in an effort to raise awareness about its endangered status. The legislation has been mired in controversy due to a dispute by House members who argue that Wehrle's salamander should be given the honor.Frank Kummer, "Seriously? Battle looms over Pa. state amphibian: Hellbender vs. Wehrle's", Philadelphia Inquirer, November 16, 2017, https://www.inquirer.com/philly/health/environment/hellbender-snot-otter-pennsylvanias-official-amphibian-20171116.html{{Cite web |url=https://www.ydr.com/story/opinion/2019/01/29/hellbender-one-step-closer-becoming-official-pa-amphibian/2712377002 |title=The hellbender is one step closer to becoming the official PA state amphibian}} The legislation did not pass in 2018, but was reintroduced in 2019.B. J. Small, "[https://www.ydr.com/story/opinion/2019/01/29/hellbender-one-step-closer-becoming-official-pa-amphibian/2712377002/ The Hellbender is One Step Closer to Becoming the Official PA State Amphibian]", York Daily Record, January 29, 2019. On April 23, 2019, Pennsylvania Governor Tom Wolf signed legislation making the eastern hellbender Pennsylvania's official state amphibian.{{Cite web | url=https://www.legis.state.pa.us/cfdocs/billinfo/billinfo.cfm?syear=2019&sind=0&body=S&type=B&bn=0009 |title = Bill Information - Senate Bill 9; Regular Session 2019-2020}} Youth members of the Chesapeake Bay Foundation's Pennsylvania Student Leadership Council were heavily involved writing and advocating on behalf of this legislation. They hope that the success of the hellbender bill in the Pennsylvania Senate will contribute to clean water efforts and raise awareness for the hellbender's struggling population.{{Cite web |last=Bulletin |first=Bay |date=2019-04-16 |title=Hellbender Poised to Become Pa. State Amphibian |url=https://www.chesapeakebaymagazine.com/hellbender-finally-poised-to-become-pa-state-amphibian/ |access-date=2023-11-07 |website=Chesapeake Bay Magazine |language=en-US}}

The hellbender faces an array of challenges that jeopardize its habitat and overall well-being. These challenges include habitat degradation, habitat modifications, pollution, and the looming threat of emerging diseases. The conservation of this species is of paramount importance to ensure its continued existence in the wild.

The hellbender faces a significant threat due to habitat degradation, primarily caused by activities like dam construction, which disrupts water flow and submerges vital riffle habitats. Logging, mining, and road construction contribute to sedimentation, covering essential nesting and shelter sites. Chemical pollutants and misconceptions about the species have led to declines. Over-collection for sale and deliberate eradication efforts have also been detrimental.

The salamander's habitat is further jeopardized by habitat modifications stemming from industrialization and urbanization, including increased stream channelization and pollution from agricultural runoff, mining, and thermal pollution. Diseases such as Batrachochytrium dendrobatidis (Bd) and Ranavirus infections have been detected in hellbender populations, contributing to population declines.

An emerging disease threat is the salamander chytrid fungus (Batrachochytrium salamandrivorans, or "Bsal"), which has caused severe declines in other salamander species. Although not confirmed in the Americas, Bsal's potential introduction poses a substantial risk. If introduced, the impacts on hellbender populations could be swift and severe, necessitating immediate mitigation measures.

{{portal|Amphibians}}

• Necturus alabamensis (Alabama waterdog)
• Necturus beyeri (Gulf coast waterdog)

{{Reflist}}

• Bishop SC (1943). Handbook of Salamanders: The Salamanders of the United States, and of Lower California. Ithaca and London: Comstock Publishing Associates, a division of Cornell University Press. 508 pp. (Cryptobranchus allegheniensis, pp. 59–62; C. bishopi, p. 63).
• Grobman AB (1943). "Notes on Salamanders with the Description of a New Species of Cryptobranchus ". Occ. Pap. Mus. Zool. Univ. Michigan (470): 1–13. (Cryptobranchus bishopi, new species).
• Petranka, James W. (1998). Salamanders of the United States and Canada. Washington and London: Smithsonian Institution Press.

Karel Čapek

War with the Newts (Válka s Mloky in the original Czech), also translated as Salamander Wars, is a 1936 satirical science fiction novel by Czech author Karel Čapek

{{Commons category|Cryptobranchus alleganiensis}}

• [https://mdc.mo.gov/discover-nature/field-guide/eastern-hellbender Hellbender Cryptobranchus alleganiensis field guide] from the Missouri Department of Conservation
• [https://web.archive.org/web/20050324225847/http://www.dgif.state.va.us/wildlife/species/display.asp?id=020020 Eastern hellbender information] at Commonwealth of Virginia.
• [https://www.dec.ny.gov/animals/7160.html Eastern Hellbender Fact Sheet] at New York State.
• [http://calphotos.berkeley.edu/cgi/img_query?query_src=photos_index&where-lifeform=any&rel-taxon=contains&where-taxon=cryptobranchus&rel-namesoup=matchphrase&where-namesoup=&rel-location=matchphrase&where-location=&rel-county=eq&where-county=any&rel-state=eq&where-state=any&rel-country=eq&where-country=any&where-collectn=any&rel-photographer=contains&where-photographer=&rel-kwid=equals&where-kwid=&max_rows=24 Cryptobranchus ] at CalPhotos.

{{Taxonbar|from=Q369467}}

Category:Amphibians of the United States

Category:Endemic amphibians of the United States

Category:Amphibians described in 1803

Category:Cryptobranchidae

Category:Extant Middle Pleistocene first appearances

Category:Natural history of the Great Smoky Mountains

Category:Taxa named by François Marie Daudin

Category:Symbols of Pennsylvania