Hellbender Salamander, Cryptoranchus alleganiensis

The hellbender salamander (Cryptoranchus alleganiensis), also known as the hellbender, is a species of giant salamander that can be found in eastern areas of North America. Its range includes the states of Ohio, Maryland, Virginia, Tennessee, Alabama, Arkansas, and some areas of Kansas and Oklahoma. This species is the sole member of its genus, Cryptobranchus, and is one of three living giant salamanders. The origin of the name hellbender is unknown and the species is locally known by many other names including mud dog, devil dog, and grampus.

The hellbender salamander can reach a length of up to two feet and is flat along its upper and lower body. It weighs between 3.3 and 5.5 pounds and is noted for its back feet, which have five toes, and for the open gill slits on each side of its body. This species holds two subspecies, known as C. a. alleganiensis and C. a. bishop, which differ slightly but are close enough to the hellbender to be classified with it.

The hellbender is thought to be a habitat specialist because it has adapted to filling in the niche of predator and prey. It can be found in fast moving waters with a variety of rocks. It requires a constant flow of water to obtain an adequate amount of oxygen. This is especially important during the first year and half of life after metamorphosis, when young hellbenders transition from larval gills to adult gills. Adults hold home ranges that do not typically overlap and each individual will defend its territory in and out of mating season. Research has shown that the species is primarily nocturnal, especially during the summer months. It consumes crayfish and small fish in varying degrees, depending upon the temperature.

The breeding season for the hellbender typically lasts from August to September, but it can extend into November in some areas of its range. During the mating season, males can be distinguished from females by the bulging ring that occurs around their cloacal glands. Males will dig under rocks to create a disk shaped nesting site and will remain there until a female enters. He will prevent her from leaving until she oviposits her eggs in the nest. This process typically takes between two and three days, during which time the female will lay between 150 and 200 eggs. The male will release his sperm over the eggs, a trait which is unique among salamanders, and will allow other females to lay eggs in the nest. Although the egg count can rise to over one thousand, cannibalism reduces those numbers dramatically. After the eggs are fertilized, the male will force the female to leave and will guard the eggs, swaying back and forth to allow more oxygen to reach them. Eggs hatch after 45 to 75 days of incubation.

The population numbers of the hellbender have been declining across its range due to many factors including disease, over harvesting for scientific and commercial purposes, and habitat destruction caused by human activities. The Ozark hellbender subspecies is protected under the Endangered Species Act and is currently the focus of a reintroduction project. The hellbender species as a whole appears on the IUCN Red List with a conservation status of “Near Threatened.”

Image Caption: Hellbender, Cryptobranchus alleganiensis, Appalachian Mountains, United States. Credit: Brian Gratwicke/Wikipedia (CC BY 2.0)