The hellbender (Cryptobranchus alleganiensis), also known as the hellbender salamander, is a species of aquatic giant salamanderendemic to the eastern and central United States. It is the largest salamander in North America. A member of the familyCryptobranchidae, the hellbender is the only extant member of the genus Cryptobranchus. Other closely related salamanders in the same family are in the genus Andrias, which contains the Japanese and Chinese giant salamanders. The hellbender, which is much larger than all other salamanders in its geographic range, employs an unusual means of respiration (which involves cutaneous gas exchange through capillaries found in its lateral skin folds), and fills a particular niche—both as a predator and prey—in its ecosystem, which either it or its ancestors have occupied for around 65 million years. The species is listed as Vulnerable on the IUCN Red List of Threatened Species due to the impacts of disease and widespread habitat loss and degradation throughout much of its range.[2]
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.[4]
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.[5] Other vernacular names include snot otter,[6] lasagna lizard,[6] devil dog, mud-devil, mud dog, water dog, grampus,[7] Allegheny alligator, and leverian water newt.[8]
C. 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. Their tail is shaped like a rudder, but it is rarely used for swimming; these salamanders use pads on their toes instead to grip rocks and walk up and down streams instead of swimming.[12] 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.[13] 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.[14] 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 125 mm in length.[15][16] Hellbenders use their lungs for buoyancy more than breathing.[12] 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.[17]
Both males and females grow to an adult length of 24 to 40cm (9.4 to 15.7in) from snout to vent, with a total length of 30 to 74cm (12 to 29in), 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).[18][19] While males and females grow at similar rates, the females tend to live longer and therefore grow larger.[20] An adult weighs 1.5 to 2.5kg (3.3 to 5.5lb), 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.[13]
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.[21][22] Easily distinguished from most other endemic salamander species simply by their size, hellbenders average up to 60cm or about 2ft in length; the only species requiring further distinction (due to an overlap in distribution and size range) is the common mudpuppy (Necturus maculosus).[23][19] 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).[21] Furthermore, the average size of C. a. alleganiensis has been reported to be 45–60cm (with some reported as reaching up to 74cm or 30 in), while N. m. maculosus has a reported average size of 28 to 40cm (11 to 16in) in length, which means that hellbender adults will still generally be notably larger than even the biggest mudpuppies.[23][24][25]
The small eyes and loose skin are characteristic of hellbenders
Skeleton and model
In captivity
Taxonomy
The genus Cryptobranchus has historically only been considered to contain one species, C. alleganiensis, with two subspecies, C. a. alleganiensis and C. a. bishopi.[19] 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.[23] 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".[23]
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.[28] In Missouri, it is estimated that the populations have declined by 77% since the 1980s.[29] Hellbender populations were listed in 1981 as already extinct 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.[27]
Ecology
Hellbenders are found in clear, clean water and their presence is an indicator that the water is good quality.[30] 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.[26] 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.[26] 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.[31] 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.[31][32] If rocks are lacking, hellbenders have been known to use holes in stream banks as habitat.[30] On average, their home range is estimated to be 198 square meters as of 2005.[33] 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.[30]
Both subspecies, C. a. alleganiensis and C. a. bishopi undergo a metamorphosis after around a year and a half of life.[26] At this point, when they are roughly 13.5cm (5.3in) 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.[13] 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.[31]
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.[34]Cannibalism of eggs is also considered a common occurrence.[19] One study found that in areas with increased deforestation, the likelihood of filial cannibalism increases.[35]
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.[34]
Life history and behavior
Behavior
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.[32] 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).[32][13] 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. [36]
Diet
C. alleganiensis feeds primarily on crayfish and small fish, but also insects, worms, molluscs, tadpoles and smaller salamanders.[37][38] A study conducted in 2017 found that larval hellbenders eat mayfly and caddisfly nymphs.[39] 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 45 and 80°F (7 and 27°C). 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.[32][26][13] When feeding on large prey items relative to themselves, it has been found that they use suction feeding.[40]
Reproduction
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. When a female approaches, the male guides or drives her into his burrow and prevents her from leaving until she oviposits.[13]
Female hellbenders lay 150–200 eggs over a two- to three-day period; the eggs are 18–20mm (0.71–0.79in) 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[41] eggs have been counted in a single nest. Males also exhibit mate and shelter guarding. Mortality rate is high for hellbender eggs.[42] 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.[13] Adult males are more likely to cannibalize their own offspring in degraded sites with limited food availability.[43]
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.[13] Males are known to show solitary parental care for the eggs and larvae for at least 7-8 months.[44]
Hatchling hellbenders are 25–33mm (0.98–1.30in) long, have a yolk sac as a source of energy for the first few months of life, and lack functional limbs.[13]
Adaptations
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.[45] Their skin also has a secretion that is important for innate immunity against chytrid activity.[46] 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.[47]
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.[2] 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.[27][25] 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.[27]
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.[27]
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.[48] 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.[49]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.[50][51][52]
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.[53]
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,[54] and Ohio.[55]
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.[56][57] The legislation did not pass in 2018, but was reintroduced in 2019.[58] On April 23, 2019, Pennsylvania Governor Tom Wolf signed legislation making the eastern hellbender Pennsylvania's official state amphibian.[59] 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.[60]
Threats
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.[2]
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.[2]
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, like Batrachochytrium dendrobatidis (Bd) and Ranavirus infections, have been detected in hellbender populations, contributing to population declines.[2]
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.[2]
Amphibians are ectothermic, anamniotic, four-limbed vertebrate animals that constitute the class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all tetrapods, excluding the amniotes. All extant (living) amphibians belong to the monophyletic subclass Lissamphibia, with three living orders: Anura (frogs), Urodela (salamanders), and Gymnophiona (caecilians). Evolved to be mostly semiaquatic, amphibians have adapted to inhabit a wide variety of habitats, with most species living in freshwater, wetland or terrestrial ecosystems. Their life cycle typically starts out as aquatic larvae with gills known as tadpoles, but some species have developed behavioural adaptations to bypass this.
Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten extant salamander families are grouped together under the order Urodela from the group Caudata. Salamander diversity is highest in eastern North America, especially in the Appalachian Mountains; most species are found in the Holarctic realm, with some species present in the Neotropical realm.
The smooth newt, European newt, northern smooth newt or common newt is a species of newt. It is widespread in Europe and parts of Asia, and has been introduced into Australia. Individuals are brown with a spotted underside that ranges in colour from orange to white. They reach an average length of 8–11 cm (3.1–4.3 in); males are larger than females. The newts' skins are dry and velvety when they are living on land, but become smooth when they migrate into the water to breed. Males develop a more vivid colour pattern and a conspicuous skin seam (crest) on their back when breeding.
The tiger salamander is a species of mole salamander and one of the largest terrestrial salamanders in North America.
The Cryptobranchidae are a family of fully aquatic salamanders commonly known as the giant salamanders. They include some of the largest living amphibians. The family is native to China, Japan, and the eastern United States. They constitute one of two living families—the other being the Asiatic salamanders belonging to the family Hynobiidae—within the Cryptobranchoidea, one of two main divisions of living salamanders.
The fire salamander is a common species of salamander found in Europe.
The common mudpuppy is a species of salamander in the family Proteidae. It lives an entirely aquatic lifestyle in parts of North America in lakes, rivers, and ponds. It goes through paedomorphosis and retains it external gills. Because skin and lung respiration alone is not sufficient for gas exchange, the common mudpuppy must rely on external gills as its primary means of gas exchange. It is usually a rusty brown color and can grow to an average total length of 13 in (330 mm). It is a nocturnal creature, and is active during the day only if the water in which it lives is murky. Its diet consists of almost anything it can get into its mouth, including insects, mollusks, and earthworms. Once a female common mudpuppy reaches sexual maturity at six years of age, she can lay an average of 60 eggs. In the wild, the average lifespan of a common mudpuppy is 11 years.
The ringed salamander is a species of mole salamander native to hardwood and mixed hardwood-pine forested areas in and around the Ozark Plateau and Ouachita Mountains of Arkansas, Oklahoma, and Missouri. This species of salamander has slander body, small head, and long tail. They are usually found to have various dorsal color from dark gray to dark brown. Various close relatives are found such as marbled salamander and spotted salamander. This species of salamander has cannibal behavior especially those in large body size.
The long-toed salamander is a mole salamander in the family Ambystomatidae. This species, typically 4.1–8.9 cm (1.6–3.5 in) long when mature, is characterized by its mottled black, brown, and yellow pigmentation, and its long outer fourth toe on the hind limbs. Analysis of fossil records, genetics, and biogeography suggest A. macrodactylum and A. laterale are descended from a common ancestor that gained access to the western Cordillera with the loss of the mid-continental seaway toward the Paleocene.
Gastrophryne carolinensis, the eastern narrow-mouthed toad, is a species of microhylid frog. It is a relatively small, toad-like amphibian found in damp, shady habitats. The species is highly fossorial, and feeds primarily on ants. These North American microhylids are distinguished from true toads, and other anurans by their moist, smooth skin, their lack of eardrums or tympana, their distinguishable squat body shape, and the unique fold of skin superior to their eyes. It is found in the United States, from southern Maryland to the Florida Keys, west to Missouri and Texas. While not a true toad, it is so called because it is terrestrial.
The Chinese giant salamander is one of the largest salamanders and one of the largest amphibians in the world. It is fully aquatic, and is endemic to rocky mountain streams and lakes in the Yangtze river basin of central China. It has also been introduced to Kyoto Prefecture in Japan, and possibly to Taiwan. It is considered critically endangered in the wild due to habitat loss, pollution, and overcollection, as it is considered a delicacy and used in traditional Chinese medicine. On farms in central China, it is extensively farmed and sometimes bred, although many of the salamanders on the farms are caught in the wild. It has been listed as one of the top-10 "focal species" in 2008 by the Evolutionarily Distinct and Globally Endangered project.
Weller's salamander is a species of salamander in the family Plethodontidae. This species in endemic to the southeastern mountain range of the United States. It is mainly found in North Carolina near Grandfather Mountain. The salamanders have a unique metallic spotting which distinguishes them from other Plethodon species and other salamanders in the area. They mainly inhabit cool forests with rocky areas.
The red salamander is a species of salamander in the family (Plethodontidae) endemic to the eastern United States. Its skin is orange/red with random black spots. Its habitats are temperate forests, small creeks, ponds, forests, temperate shrubland, rivers, intermittent rivers, freshwater, trees springs. Overall this species is common and widespread, but locally it has declined because of habitat loss and it is considered threatened in Indiana and New York. Red salamanders eat insects, earthworms, spiders, small crustaceans, snails, and smaller salamanders. To eat, they extend their tongue to capture prey on the tip of it and retract it back into their mouths. The red salamander, as a member of the family Plethodontidae lacks lungs and respires through its skin.
The spotted-tail salamander, also known as a "cave salamander", is a species of brook salamander.
The reticulated flatwoods salamander is a species of mole salamander, an amphibian in the family Ambystomatidae. The species is native to a small portion of the southeastern coastal plain of the United States in the western panhandle of Florida and extreme southwestern Georgia. The species once occurred in portions of southern Alabama but is now considered extirpated there. Its ecology and life history are nearly identical to its sister species, the frosted flatwoods salamander. A. bishopi inhabits seasonally wet pine flatwoods and pine savannas west of the Apalachicola River-Flint River system. The fire ecology of longleaf pine savannas is well-known, but there is less information on natural fire frequencies of wetland habitats in this region. Like the frosted flatwoods salamander, the reticulated flatwoods salamander breeds in ephemeral wetlands with extensive emergent vegetation, probably maintained by summer fires. Wetlands overgrown with woody shrubs are less likely to support breeding populations.
Stanley E. Trauth is an American herpetologist and professor of zoology and environmental studies at Arkansas State University. He is also the curator of the herpetological collection of the Arkansas State University Museum of Zoology.
The Ozark hellbender is a subspecies of the hellbender. The subspecies is strictly native to the mountain streams of the Ozark Plateau in southern Missouri and northern Arkansas. Its nicknames include lasagna lizard and snot otter. This large salamander grows to a total length of 29–57 cm (11–22 in) over a lifespan of 30 years. The Ozark hellbender is a nocturnal predator that hides under large flat rocks and primarily consumes crayfish and small fish. As of 2011, the U.S. Fish and Wildlife Service (USFWS) has listed the subspecies as endangered under the Endangered Species Act of 1973. The population decline of the subspecies is caused by habitat destruction and modification, overutilization, disease and predation, and low reproductive rates. Conservation programs have been put in place to help protect the subspecies.
References
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1 2 Sofia, Madeline K. (September 14, 2017). "Snot Otters Get A Second Chance In Ohio". NPR. Snot otter. Lasagna lizard. Pick your favorite nickname for the Eastern hellbender salamander.
↑ Nickerson, Max Allen; Mays, Charles Edwin (1973). The Hellbenders: North American "Giant Salamanders". Publications in Biology and Geology. Milwaukee Public Museum.
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1 2 Humphries, Jeffrey W; & Pauley, Thomas K. (2005). Life History of the Hellbender, Cryptobranchus alleganiensis, in a West Virginia Stream. The American Midland Naturalist, 154(1), 135–142. https://doi.org/10.1674/0003-0031(2005)154[0135:LHOTHC]2.0.CO;2
↑ Pugh, M. W.; Groves, J.D.; Williams, L.A.; Gangloff, M.M. (2013). "A previously undocumented locality of eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) in the Elk River, Carter County, TN". Southeastern Naturalist. 12 (1): 137–142. doi:10.1656/058.012.0111.
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↑ Gehlbach, Frederick R. (1960). "Comments on the Study of Ohio Salamanders with Key to Their Identification". Journal of the Ohio Herpetological Society. 2 (3): 40–45.
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↑ Albanese, Brett; Jensen, John B.; Unger, Shem D. (2011). "'Occurrence of the Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis) in the Coosawattee River System (Mobile River Basin), Georgia". Southeastern Naturalist. 10 (1): 181–184. doi:10.1656/058.010.0116. S2CID84971915.
↑ 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
1 2 3 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.
1 2 3 4 Humphries, W.J.; Pauley, T.K. (December 2000). "Seasonal Changes in Nocturnal Activity of the Hellbender, Cryptobranchus alleganiensis, in West Virginia". Journal of Herpetology. 34 (4): 604–607. doi:10.2307/1565279. JSTOR1565279.
↑ 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
↑ Hopkins, William A., et al. "Filial cannibalism leads to chronic nest failure of eastern hellbender salamanders (Cryptobranchus alleganienesis)." The American Naturalist 202.1 (2023).
↑ 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.
↑ 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)
↑ Chris Mattison (2005). Encyclopedia of Reptiles and Amphibians. The Brown Reference Group. p.23.
↑ 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.
↑ Mattison, Chris (2005). "What is an amphibian?". Encyclopedia of Reptiles and Amphibians. Rochester, Kent: Grange Books. p.22. ISBN978-1-84013-794-1.
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
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The small eyes and loose skin are characteristic of hellbenders
Skeleton and model
In captivity
