hellbender

Hellbender
Conservation status
Near Threatened (IUCN 3.1)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Amphibia Subclass: Lissamphibia Order: Caudata Family: Cryptobranchidae Genus: Cryptobranchus Species: C. alleganiensis
Binomial name
Cryptobranchus alleganiensis Daudin, 1803
Subspecies
C. a. alleganiensis (Eastern Hellbender) C. a. bishopi (Ozark Hellbender)

The hellbender (Cryptobranchus alleganiensis) is a giant salamander, native to North America. which inhabits large, swiftly flowing streams with rocky bottoms. It is the monotypic species within Cryptobranchus, with two subspecies.

Contents 1 Etymology 2 Physical description 3 Range 4 Habitat 5 Reproduction 6 Diet 7 Predation 8 Conservation status 9 Notes 10 References 11 External links 11.1 Media only

Etymology

The origin of the name "hellbender" is unclear. The Missouri Department of Conservation says:

"The name 'hellbender' probably comes from the animal’s odd look. Perhaps it 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."^[1]

Vernacular names include "snot otter", "devil dog", "mud-devil", "grampus", "Allegheny alligator", "leverian water newt", and "vulgo".^[2][3] The genus name is derived from the Ancient Greek, "kryptos" (hidden^[4]) and "branch" (lung); a reference to oxygen absorption primarily through side-frills and not lungs.^[5]

Physical description

Hellbenders exhibit no sexual dimorphism, and both males and females grow to an adult length of 24 centimetres (9.4 in) to 40 centimetres (16 in) from snout to vent, with a total length of 30 centimetres (12 in) to 74 centimetres (29 in) making it the third largest aquatic salamander species in the world (next to the Chinese Giant Salamander and the Japanese Giant Salamander) and largest in the North America^[6]. An adult weighs 1.5 kilograms (3.3 lb) to 2.5 kilograms (5.5 lb). Hellbenders reach sexual maturity at about five years of age, and may live thirty years in captivity. They have powerful jaws that can inflict a painful bite.

C. alleganiensis have flat bodies and heads, with beady dorsal eyes and slimy skin. Like most salamanders, they have short legs with four toes on the front legs and five on their back appendages, and their tails are keeled to propel them through water. 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.^[1] They are blotchy brown or red-brown in color, with a paler underbelly.

Hellbenders are completely aquatic, and although active on cloudy days, they are primarily nocturnal.

Range

The range of the eastern hellbender (C. a. alleganiensis) in North America extends from southwestern and south central New York, west to southern Illinois, and south to extreme northeastern Mississippi and with a heavy population in Eastern Tennessee the northern parts of Alabama and Georgia. A disjunct population occurs in east-central Missouri. The Ozark hellbender (C. a. bishopi) subspecies exists as a disjunctive population in southeastern Missouri and adjacent northeast Arkansas. They also live in Western Virginia

Habitat

Hellbenders inhabit large, fast-flowing, rocky streams below 750 metres (2,500 ft) in elevation. They can usually be found beneath large rocks in shallow rapids. They are less abundant in deeper areas of a stream, or areas which do not have flat piled rocks that offer them cover.

By day C. alleganiensis stay under rocks or fallen logs, occasionally sticking their heads out. They may come out during breeding season or on overcast days to move about the stream. Most remain within a range of a few hundred square meters, although journeys of 3,500 metres (2.2 mi) by adults have been observed. They defend the rocks they live under from other hellbenders, and rarely share homes.

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. During this time the male develops swollen 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.^[7]

Female hellbenders lay 150-200 eggs over a 2- to 3-day period; the eggs are 18-20 mm in diameter, connected by 5-10 mm cords. As the female lays eggs the male positions himself alongside or slightly above them, spraying the eggs with seminal fluid while swaying his tail and moving his hind limbs, which disperses the sperm uniformly. Cannibalism leads to a much lower number of eggs in hellbender nests than would be predicted by ovarian counts.

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 45-75 days, depending on region. It is not surprising if the male or other Hellbenders eat the eggs before they are hatched.

Hatchling hellbenders are 25 millimetres (0.98 in) to 33 millimetres (1.3 in) long, have a yolk sac as a source of energy for the first few months of life, and lack functional limbs.

Diet

Crayfish and small fish are the main food items consumed by Hellbenders. This diet changes little seasonally. They also eat mollusks, worms, and insects. Specimens have been found containing lamprey, tadpoles, aquatic reptiles, and even one containing a toad and another with a small mammal. Adults will eat their shed outer skin, their own eggs, the eggs of others, and even hatchlings of their own species, along with other adults smaller than them.

Predation

Immature hellbenders are preyed upon by large fish, turtles, and water snakes. Native Americans used them as a food source in the past. Often they are inadvertently caught by fishermen with baited hooks. Young Hellbenders are sometimes preyed upon by larger Hellbenders.

Conservation status

Hellbenders have been classified an endangered species in Illinois, Indiana, Maryland, Missouri and Ohio, and "rare" or "of special concern" in Georgia, Kentucky, New York, North Carolina, Virginia and West Virginia. Since the 1970's U.S. populations have declined an average of 77%.^[8] Globally, the species was "Near threatened" according to the 2004 IUCN Red List^[9]

This decline in population is due to:^[8]

• an increase in the number of dams;
• reduced water quality (through pollution and siltation);
• removal for use as exotic pets (a growing trade in China and Japan, where the animal can be sold for up to $1700);
• persecution by anglers, who erroneously believe the Hellbenders to be destroying trout fisheries;
• Increased Chytridiomycosis infestions especially in the Western parts of the United States.

Notes

Reason they suffer: No place to hide from the current of the waters. Cure: place many man made or natural shelters in the waters. The more shelters, the more they will come back in great numbers.

References

• Hammerson & Phillips (2004). Cryptobranchus alleganiensis. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Database entry includes a range map and justification for why this species is threatened.
• Petranka, James W. (1998) Salamanders of the United States and Canada, Washington and London: Smithsonian Institution Press.

External links

Wikispecies has information related to: Cryptobranchus alleganiensis

• http://www.hellbenders.org
• http://www.ozarkhellbender.com
• Cryptobranchid Interest Group
• Eastern hellbender information at Commonwealth of Virginia
• Eastern Hellbender Fact Sheet at New York State
• Ozark Hellbender at U.S. Fish & Wildlife Service
• Amiphibiaweb Entry for the Hellbender
• Official Arkansas State University mascot comment page
• Arkansas Business article on the Hellbender grass roots effort

Media only

Wikimedia Commons has more pictures of: Cryptobranchus

• Cryptobranchus at CalPhotos
• http://www.hellbenders.org/photos.html