Illinois Natural History Survey - University of Illinois



Susan Post


In a few Illinois streams a large, cryptically colored salamander can be found—the hellbender, Cryptobranchus alleganiensis. Hellbenders are the largest salamanders in North America and the third largest in the world. Adults range in length from 11 to 29 inches and may weigh four to five pounds. They are fully aquatic and cannot live out of water.

Hellbenders have wide, flat heads with tiny lidless eyes and paddlelike tails. These salamanders have no external gills, instead they have folds of skin which help them take in oxygen from the water. These folds cover their bodies and their short, thick legs. While their bellies are usually only one color—yellowish-brown—the rest of their bodies are a combination of browns or grayish browns with dark blotches. During the breeding season hellbenders may have an overall reddish brown color.

Illinois Natural History Survey herpetologist Phil Smith described hellbenders as, “ugly in appearance and unpleasant to handle because of their extreme sliminess.” This slime makes them very hard to catch and handle. Scientists think that the skin secretions keep the hellbenders free from infections, protect against predators, and decrease the friction of fast flowing water.

Hellbenders are found in the Appalachian and Ozark Mountain regions, from southern New York state to northern Georgia and west to Missouri. They have been found in southern and southeastern Illinois. They live in cool, clear streams with moderate to fast currents. The water is usually one to three feet deep and is a mix of faster flowing rapids and slower runs and pools. The rocky riffles help oxygenate the water. Large, flat rocks or bedrock with openings in shallow water are also important, as the hellbenders use these for shelter. Keeping their habitat protected from pollution, excessive siltation, and other degradations is key for hellbender survival.

Hellbenders are nocturnal, secretive, and seldom observed. They will walk along stream bottoms but most of their time is spent hiding under large, flat rocks. As water flows over their bodies, oxygen is taken up by tiny blood vessels in their skin and carbon dioxide is released. Hellbenders have lungs and are capable of gulping air from the surface; however, their lungs are mainly used for buoyancy.

They will eat a variety of aquatic prey, such as small fish and insects; yet, 90% of their diet consists of crayfish.

Courtship and breeding take place during late summer or early autumn. During this time hellbenders increase their activity and may actually be seen walking around on the bottoms of streams. Females will reach breeding age at seven or eight years of age and may breed only every second or third year. Males breed at a younger age. In the fall the males will excavate cavities (nest sites) under large rocks. The female will lay her eggs in a long strand (similar to a strand of beads) in a cluster in the nest site. The male will then come and fertilize the eggs externally, much like a fish. Once the female has laid her eggs, the male forces her out of the nest and he stays and guards the eggs, protecting them from other hellbenders that would eat them. The eggs will swell to ping-pong ball size and hatch in four to six weeks. The newly hatched larvae are less than one inch in length. The larvae have streamlined bodies, short gills, and low tail fins. Once they begin to eat small aquatic invertebrates, the larvae will turn dark brown or black. By their second year the larvae are four to five inches in length and have lost their gills. The larvae spend most of their time hiding in stream gravel niches. Hellbenders can live for 30 to 35 years.

Hellbenders have a variety of nicknames based on appearance and/or location. These include mud cat, walking catfish, Allegany alligator, snot-otter, mud devil, and mountain alligator. The common name of hellbender is thought to have originated with early settlers who upon seeing the organism’s odd look, thought it was a creature from hell and bent on returning.


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