Hellbender

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For other uses, see Hellbender (disambiguation).
Hellbender

Conservation status
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 large salamander, native to North America, which inhabits large, swiftly flowing streams with rocky bottoms. Vernacular names include "snot otter", "devil dog", and "Allegheny alligator". The reason for its name "hellbender" is not very clear. The Missouri Department of Conservation says: [1]

“ 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. ”

Contents

[edit] 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 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 disjunct population in southeastern Missouri and adjacent northeast Arkansas.

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 and Virginia. This decline in population is because of reduced habitat due to stream impoundment, pollution, and siltation.

[edit] Anatomy & Physiology

Hellbenders exhibit no sexual dimorphism, and both males and females grow to an adult length of 24 to 40 cm (9 in to 16 in) from snout to vent, with a total length of 30 to 74 cm (12 in to 29 in) making it the 3rd largest aquatic salamander species in the world (next to the Chinese Giant Salamander and the Japanese Giant Salamander) and largest in the North America[2]. An adult weighs 1.5 to 2.5 kg (3 to 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.

Hellbenders have flat bodies and heads, with beady dorsal eyes and slimy skin. Like all salamanders, they have short legs with four toes on the front legs and five on their back ones, and their tails are keeled to propel them through water. Although the hellbender has working lungs, only immature ones have gills; the hellbender absorbs oxygen from the water through capillaries of its side-frills.[3] 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.

[edit] Habitat

Hellbenders inhabit large, fast-flowing, rocky streams below 750 m 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 hellbenders 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 3500 meters by adults have been observed. They defend the rocks they live under from other hellbenders, and rarely share homes.

[edit] 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.

[edit] Predators

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.

[edit] Evolutionary History

Very little is known about this mysterious salamander. It is only known that they appeared in Japan, parts of China, and Eastern North America. The fossils of the genus Cryptobranchus cannot be traced back in time, there is too little evidence. Currently, only 2 subspecies in North America are known; Cryptobranchus alleganiensis and Cryptobranchus alleganiensis a. bishopi.

[edit] 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.[4]

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 25-33 mm long, have a yolk sac as a source of energy for the first few months of life, and lack functional limbs.

[edit] Mythology

The hellbender has gotten the nicknames "devil dog" and "Allegheny alligator" because the giant ugly salamander is often encountered by surprised fishermen, under rocks or on the end of a baited line. Folklore claims that hellbenders smear fishing lines with slime, drive game fish away, and inflict a poisonous bite, but, in fact, apart from the (non-poisonous) bite and toxin (a very small amount, but do not touch your eyes after that) on its skin, hellbenders are harmless. If Hellbenders live in a stream, it shows that it is in excellent quality.

[edit] Pop Culture

Recently a group of Arkansas State University alumni tried, apparently unsuccessfully, to convince the school to change the mascot to the Hellbender after ASU decided a mascot change was in order due to pressure from the NCAA. [5] [6] [7]

[edit] Notes

  1. ^ The Hellbender
  2. ^ AmphibiaWeb - Cryptobranchus alleganiensis
  3. ^ The Hellbender
  4. ^ Question regarding solitary-pair brood nests, is contradicted by some of the reference sites and requires further checking.
  5. ^ http://www.astate.edu/mascot/comments.html
  6. ^ http://www.arkansasbusiness.com/sports_article.asp?aID=100941.90247.113060/
  7. ^ Page 1

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