Hellbender
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| Cryptobranchus alleganiensis Daudin, 1803 |
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C. a. alleganiensis (Eastern Hellbender) |
The Hellbender (Cryptobranchus alleganiensis) is a large aquatic salamander native to North America whose habitat includes large, swiftly flowing streams with rocky bottoms. Common names include the "snot otter" and "devil dog."
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[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 northwest Arkansas.
Hellbenders are considered endangered in Illinois, Indiana, Maryland, and Ohio and rare or of "special concern" in Georgia, 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 have a flat body and head, with small eyes. Like all salamanders, they have short legs and thin bodies. Their tails, however, are especially keeled to help propel them through water. They have four toes on their front legs and five on their back ones. Although the Hellbender has working lungs, there is a single gill slit along each side of its neck, resembling fleshy folds. The male and female are about the same size, from 30 cm to a record 73 cm, measured from the tip of the snout to the tip of the tail. Hellbenders are completely aquatic and are nocturnal. They weigh about three to five pounds. They have powerful jaws that can inflict a painful bite. Slimy secretions which they produce can be noxious to some of their predators. Hellbenders may live up to twenty-nine years in captivity, and follow a normal amphibious life cycle.
[edit] Habitat
Hellbenders inhabit large, fast-flowing, rocky streams below 762 m in elevation. Most frequently 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 which can easily provide cover.
They stay under cover of rocks or other large submerged objects by day, occasionally sticking their heads out. They may leave this cover during breeding season or on overcast days to move about the stream. Most remain in an area of up to a few hundred m2. Although journeys of 3500 m by adults have been observed. The rocks they live under are defended from other Hellbenders, and rarely do they 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, squatic 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 larvae of their own species.
[edit] Predators
Hellbenders are preyed upon by large fish, turtles, and water snakes. Native Americans have also used them as a food source in the past. Often they are caught by fishermen on baited hooks.
[edit] Reproduction
The breeding season begins in late August or early-mid September and extends to October-late November, depending on region. During this time the male will develop swolen cloacal glands. Contrary to most salamanders, the Hellbender preforms external fertilization. Before mating, males move to an individual brooding site, which is normally an excavated, saucer-shaped depression under a rock or log. The entrance is positioned out of the direct current and usually points downstream. Males remain in these brooding sites awaiting females. When a female approaches, the male will guide or drive her into his burrow. He then may agressively prevent her from leaving until she oviposits. As eggs are being laid by the female, the male positions himself alongside or slightly above the female. He then sprays the eggs with seminal fluid while swaying his posterior end and moving his hindlimbs to ensure he disperses sperm uniformly over the eggs.
Females lay anywhere between 150 and 200 eggs in a 2 to 3-day period. These eggs are 18-20 mm in diameter and separated by 5-10 mm adjoining cords. Egg cannibalism leads to a much lower amount present in nests as compared to ovarian counts.
The male drives the female away from the nests after they have oviposited but then guards the eggs for an undertermined amount of time. Icubating males will rock back and forth and and undulate their lateral folds, increasing oxygen supply to the eggs and the adult. Incubation lasts from 45-75 days depending on region. The hatchlings which emerge after this period 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] External links and references
- Commonwealth of Virginia Hellbender Information
- State of New York Hellbender Information
- U.S. Fish & Wildlife Service Endangered Species Program
- Georgia Wildlife Web
- The Hellbender Homepage
- The Ozark Hellbender Hompage
- Amiphibiaweb Entry for the Hellbender
[edit] 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 near threatened
- Petranka, James W. (1998) Salamanders of the United States and Canada, Washington and London: Smithsonian Institution Press.
