Hellbender (Cryptobranchus alleganiensis): Giant Salamander Facts

What does a hellbender look like?

A hellbender looks like a salamander that has been flattened. Its head is broad and flat, its body is wide and low, and its short, stout legs end in four toes on the front feet and five on the back feet. The tail is flattened from side to side like a rudder.

The most striking feature is the skin. Thick, loose folds run along each side of the body from the neck to the tail, and the legs carry flaps of skin too. The skin is covered in mucus, so a hellbender feels very slippery. Colors range from gray and olive brown to reddish brown, often with darker blotches, and the belly is paler.

The eyes are tiny, set on top of the head and have no eyelids. Adults have no external gills, although most keep a small gill slit on each side of the neck. This hidden gill opening gave the genus its name: Cryptobranchus means “hidden gill” in Greek.

How big is a hellbender?

Hellbenders are giants among the salamanders of the Americas. Adults usually measure 30–60 cm (12–24 in) from snout to tail tip, and exceptional animals reach about 74 cm (29 in). Weights range from about 0.4 kg to 2.5 kg (0.9–5.5 lb), depending on the animal’s length and condition.

Males and females look alike, though females tend to live longer and so can grow larger. The Ozark hellbender of Missouri and Arkansas averages a little smaller than the eastern hellbender. Only the giant salamanders of China and Japan, close relatives in the same family, grow larger; the Chinese giant salamander can exceed 1.5 m (5 ft).

Hellbender or mudpuppy?

The only other large salamander likely to be confused with a hellbender in its streams is the common mudpuppy (Necturus maculosus). The two are easy to tell apart with a good look:

• Gills: mudpuppies keep bushy, dark red external gills behind the head all their lives; adult hellbenders have none.
• Toes: mudpuppies have four toes on every foot, while hellbenders have five on each hind foot.
• Skin and shape: hellbenders are flatter, with thick, wrinkly skin folds along the sides; mudpuppies are smoother and more rounded, often with dark spots.
• Size: adult mudpuppies usually measure about 20–40 cm (8–16 in), so a large hellbender is clearly bigger.

Young hellbenders still have external gills, so very small animals are best told apart by their toes.

Where do hellbenders live?

Hellbenders are found only in the United States. The eastern hellbender (C. a. alleganiensis) ranges from southern New York and Pennsylvania through Ohio, West Virginia, Kentucky, Virginia, Tennessee and North Carolina to northern Georgia and Alabama, with outlying populations west to Indiana, Illinois and east-central Missouri. The Ozark hellbender (C. a. bishopi) lives in the White River and Spring River systems of southern Missouri and northern Arkansas.

Within that range they are true habitat specialists. They need clear, cool, well-oxygenated streams and rivers with riffles and plenty of large, flat rocks that are not buried in silt. Each hellbender shelters under its own rock by day, and its presence is a good sign that a stream is healthy. Slow, muddy or warm water does not suit them.

Hellbenders are fully aquatic and almost never leave the water. One reason they need fast, cold water is the way they breathe: most of their oxygen passes in through their skin, which works best in water rich in oxygen. The details are explained in How do hellbenders breathe?

What do hellbenders eat?

Crayfish are the hellbender’s main food, and in many streams they make up the bulk of the diet. Hellbenders also eat small fish, aquatic insects, worms, snails, tadpoles and smaller salamanders, and they scavenge dead fish. Larvae feed on the nymphs of mayflies, caddisflies and other stream insects.

Hellbenders are mostly sit-and-wait hunters. They lie under a rock with only the head showing and lunge at prey that comes close, sucking it in with a sudden opening of the wide mouth. At night they also walk slowly along the streambed searching for food. Their eyesight is poor, so they rely on smell and on a lateral line, a row of sense organs like that of fish, which picks up movement in the water.

Behavior

Hellbenders are solitary and mainly nocturnal. They spend the day hidden under a flat rock or log, often with the same shelter used for long periods, and come out after dark to feed. Adults defend their shelter rock against other hellbenders, and two animals are rarely found under the same rock outside the breeding season.

Despite the rudder-shaped tail, hellbenders are not strong swimmers. They usually walk along the bottom, gripping rocks with their toes and using their flat shape to slip through the current and into narrow crevices. Their skin contains light-sensitive cells, especially on the tail, which may help them keep their whole body hidden under a rock.

Reproduction and life cycle

Hellbenders breed in late summer and fall, mainly from late August to November depending on the region. Unlike most salamanders, they use external fertilization, like many fish. Each male digs a saucer-shaped nest under a large rock and waits at the entrance for a female.

A female lays about 150–450 eggs in long strings, and the male releases sperm over them as she lays. Afterward he drives her away and guards the nest, sometimes adding the eggs of several females, for about 45–80 days until the eggs hatch. Guarding males rock their bodies and ripple their skin folds to keep oxygen-rich water flowing over the eggs. Males do sometimes eat some of the eggs, especially at degraded sites with little food.

Hatchlings are only 2.5–3.3 cm (1–1.3 in) long and live off their yolk at first. Young hellbenders keep feathery external gills until they are around 18 months old and about 10–13.5 cm (4–5.3 in) long. They reach maturity at about 5–8 years of age.

How long do hellbenders live?

Hellbenders are long-lived for amphibians. Animals that survive to adulthood commonly live 12–15 years in the wild, and some probably reach 25–30 years. In captivity, hellbenders have lived about 29–30 years. Very few young survive their first years, because eggs and larvae are eaten by fish and other predators.

Predators and threats

Fish such as bass and trout, turtles, water snakes and even other hellbenders prey on eggs, larvae and young hellbenders. Large adults have few natural enemies, protected by their size, their hiding places and their foul-tasting skin mucus.

The serious threats come from people. Silt washed off cleared land, farms and construction sites smothers the rocks and gravel hellbenders need. Dams turn fast streams into slow, warm reservoirs and split populations. Pollution, loss of streamside forest, disease (including chytrid fungus and ranavirus), illegal collecting and killing by anglers who mistake them for pests have all played a part. Warmer streams hold less oxygen, so climate change adds to the pressure.

Conservation status

The IUCN Red List classifies the hellbender as Vulnerable, with a decreasing population. Surveys across its range have found many populations in steep decline, often made up mainly of old adults with few young animals. In Missouri, both hellbender subspecies are estimated to have declined by about 75–80 percent since the 1970s and 1980s.

In the United States, the Ozark hellbender has been listed as endangered under the Endangered Species Act since 2011, and the Missouri population of the eastern hellbender since 2021. Zoos and wildlife agencies run head-starting programs that raise eggs collected from the wild and release young hellbenders when they are larger and safer. The full story is in Is the hellbender endangered?

Myths and facts

Myth: hellbenders are venomous. Hellbenders have no venom and pose no danger to people. Their skin mucus is unpleasant to predators, but the animal itself is shy and harmless if left alone.

Myth: hellbenders ruin fishing. Anglers have often killed hellbenders in the belief that they eat game fish or their eggs. In fact, hellbenders feed mainly on crayfish, and their presence shows that a stream has the clean water that trout and other fish also need.

Fact: hellbenders are amphibians, not lizards. Nicknames such as Allegheny alligator suggest a reptile, but hellbenders are salamanders with smooth, moist skin and no scales. The story of these names is in Why is it called a hellbender?

Hellbenders and people

Hellbenders were described by science in 1803, and their dramatic name was already in use among settlers in the Appalachians around that time. Folk names such as snot otter, devil dog and mud-devil show how strange the animal looked to the people who found it.

Today the hellbender has become a symbol of clean rivers. Pennsylvania made the eastern hellbender its official state amphibian in 2019, and schools, anglers and volunteers help with stream cleanups and surveys. Anyone who finds a hellbender should leave it and its rock undisturbed, since lifting rocks can destroy nests and shelters.