Amphibians
Giant Salamander
Cryptobranchidae · also called hellbender
A giant salamander is what a salamander becomes when nothing forces it to stay small. It is the largest amphibian alive, a slab-headed, loose-skinned animal that lies under a rock in a cold river for decades, breathing through the wrinkles in its own hide, waiting for a crayfish to come close enough to snap.
Overview
Giant salamanders are the family Cryptobranchidae, just a handful of species split between Asia and eastern North America. The Chinese giant salamanders can pass 1.8 m and 50 kg, the Japanese giant salamander reaches about 1.5 m, and the North American hellbender, the smallest, still grows to 70 cm — far bigger than any other salamander on its continent. All live in cold, fast, rocky streams and are carnivores.
Skin as a lung
Adults lose their gills and have tiny, near-useless lungs, so they take in almost all their oxygen through the skin. The heavy folds along their flanks add surface area for this, and an animal short of oxygen sways to move fresh water past them. This ties the whole family to cold, turbulent, oxygen-rich water and makes it fast to suffer from warming or pollution.
Guarding fathers, long lives
A large male digs a den under a rock, draws in several females to lay egg strings, fertilises them externally, and then guards the clutch alone for months, fanning it and eating mouldy eggs. Giant salamanders can outlive a human, with documented ages past 50.
In the dark
With tiny lidless eyes, a giant salamander hunts by ripples and smell, reading water movement through a line of sensory nodes down its body like a fish’s lateral line.
Status
The Chinese giant salamanders are Critically Endangered, down more than 80 per cent and possibly gone from most of their range, hunted for luxury meat and swamped by farm escapes. The Japanese giant salamander is Near Threatened and protected; the hellbender is declining sharply, with the Ozark population federally endangered.
Giant Salamander: common questions
How big do giant salamanders actually get?
They are the largest amphibians in the world by a wide margin. The South China giant salamander is the record holder, with reliable historical accounts of animals over 1.8 metres and around 50 to 60 kilograms, though few if any that size survive today. The Japanese giant salamander commonly reaches 1 to 1.5 metres. The North American hellbender, the smallest of the family and the only one outside Asia, still grows to 60 to 74 centimetres, which makes it by far the biggest salamander on its continent. All three dwarf the next largest amphibians, such as the African bullfrog and the Chinese and Japanese newts, and they look startlingly prehistoric because the body plan really has changed little in around 170 million years.
How does a giant salamander breathe underwater as an adult?
Almost entirely through its skin. Unlike some other large aquatic salamanders, giant salamanders lose their external gills when they leave the larval stage, and their lungs are small and used mainly for buoyancy rather than gas exchange. Oxygen instead diffuses directly from the water into a dense network of blood vessels just under the skin. The loose, wrinkled folds running along the flanks, which give the animals their baggy appearance, are an adaptation to increase skin surface area, and a salamander short of oxygen will sway its body to move fresh water past them. This is why the group can only live in cold, turbulent, highly oxygenated streams and is so quickly harmed by warming or stagnant water.
Why are Chinese giant salamanders so endangered?
Because they became a luxury food. Their meat is prized in parts of China and can command very high prices in restaurants, which created a strong incentive to catch every wild animal that could be found and, from the 1990s, to farm them on an industrial scale. Wild populations, already hurt by dams, pollution, and the loss of clean mountain streams, were hunted down by an estimated 80 per cent or more. The huge farming industry has not relieved the pressure, since farms restock from wild-caught animals and release or lose stock that then swamps the remaining wild populations with mixed and possibly maladapted genes. Recent surveys of dozens of sites across the range found almost no wild salamanders at all.
What is the difference between a giant salamander and an axolotl or a hellbender?
The hellbender is a giant salamander, the North American member of the family Cryptobranchidae, and shares the wrinkled skin, flat head, skin breathing, and stream habitat of its Asian relatives. The axolotl is a different animal, a Mexican mole salamander in the family Ambystomatidae, famous for keeping its feathery external gills and larval form for life, a condition called neoteny, and for living in a single lake system near Mexico City. Giant salamanders do metamorphose, losing their gills, and are many times larger. Both, however, are among the most threatened amphibians in the world, the axolotl Critically Endangered in the wild despite being abundant in captivity.