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Giant salamander

life science Maturity 5-7 Next article →

Giant salamanders belong to the family Cryptobranchidae. They are among the largest living amphibians in the world. These animals are fully aquatic, meaning they spend their entire lives in the water. You can find them living in China, Japan, and the eastern United States. Within the larger division of salamanders called Cryptobranchoidea, they are one of two living families. The other family is the Asiatic salamanders, known as Hynobiidae.

2009 Andrias davidianus
2009 Andrias davidianus

The way these animals breathe is quite unique. Most adult giant salamanders have poorly developed lungs. They also lack traditional gills, though they show paedomorphic traits. Paedomorphism means they do not complete a full metamorphosis from larvae to adults. Because of this, adults often retain gill slits. To compensate for their breathing needs, they have large folds of skin along their flanks. These folds increase the animal's surface area. This allows them to absorb more oxygen from the water through capillaries in the skin. This process is why the family name comes from the Greek words for "hidden" and "gill."

There are different types of giant salamanders found in different regions. The genus Andrias contains the largest species and is native to East Asia. One example is the South China giant salamander, or Andrias sligoi. Another is the Japanese giant salamander, known as Andrias japonicus. This species can grow quite large and has been known to live for over 50 years in captivity. In the United States, you will find the hellbender. The hellbender belongs to the genus Cryptobranchus and is the only member of that specific group.

Giant salmander
Giant salmander

These salamanders have a very long evolutionary history. The oldest known fossils of cryptobranchoids date back to the Middle Jurassic in China. A creature called Chunerpeton is suggested to be one of the oldest. Over millions of years, these lineages moved across the world. Scientists believe they reached the eastern United States via a land bridge. This process allowed them to spread through adaptive radiation.

Andrias Scheuchzeri Oeningen
Andrias Scheuchzeri Oeningen

One famous moment in their discovery involved a Swiss physician named Johann Jakob Scheuchzer. In 1726, he described a fossil that he believed was a human drowned in a biblical flood. He called it Homo diluvii testis. However, in 1812, Georges Cuvier examined the fossil and realized it was not human. It was actually a salamander. It was later renamed Salamandra scheuchzeri in 1831. In 1839, Tschudi coined the genus name Andrias. This name means "image of man," which honors Scheuchzer's original mistaken belief.

Andrias Scheuchzeri Oeningen
Andrias Scheuchzeri Oeningen

Feeding and survival require special adaptations. Giant salamanders are mostly nocturnal, so they hunt at night. They have very small eyes and bad eyesight. To find food, they use sensory nodes on their heads and bodies. These nodes detect tiny changes in water pressure. This helps them locate prey like fish, frogs, crabs, and shrimp. While they are aquatic, they are actually poor swimmers. They usually walk along the bottom of the water. They only use undulatory locomotion, or wavy body movements, for short escapes.

2009 Andrias davidianus
2009 Andrias davidianus

Reproduction is a dedicated process for these animals. During mating season, they travel upstream to spawn. A female can lay two strings of eggs, with each string containing over 200 eggs. The male fertilizes the eggs externally by releasing sperm onto them. He then guards the eggs for at least three months until they hatch. The male may also use tail fanning to increase the oxygen supply for the eggs. Only large males can occupy and guard a den. They protect the den from other males and inactive females.

Giant salmander
Giant salmander

Today, these animals face challenges in their natural habitats. In Japan, dam-building threatens their environment. To help, some dams have been fitted with ramps and staircases. These allow the salamanders to move upstream to their spawning areas. Understanding their biology and history helps us protect these ancient survivors. Their presence in our rivers connects us to a lineage that has existed for tens of millions of years.

2009 Andrias davidianus
2009 Andrias davidianus
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File:2009_Andrias_davidianus.JPG
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File:Andrias Scheuchzeri Oeningen.jpg
Andrias Scheuchzeri Oeningen.jpg
File:Giant salmander.jpg
Giant salmander.jpg
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