The Amphibian That Roams Rivers; The Giant Japanese Salamander

Japan has its fair share of unique animals – some harmless, others, intimidating – that roam its islands. As a source of folklore and legends from hundreds of years ago, many of these animals still exist in Japan today. One example of an amphibian that has a notable spot in Japan’s history and tales is the Japanese giant salamander.

By RedGazelle15 (Own work) [CC BY-SA 4.0 (], via Wikimedia Commons

Fun Facts: The Habitat, Size, and Life of the Japanese Giant Salamander

Found exclusively in Japan, the Japanese giant salamander is a huge amphibian that usually located in the western regions of Honshu, Shikoku, and Kyushu. It is called “Osanshouo” by the locals, written as “オオサンショウウオ/大山椒魚” in Japanese. 

It’s been around for millions of years, so its discovery is not new. It is endemic to Japan and holds second place when it comes to largest amphibian species currently existing, right next to the champion, the Chinese giant salamander, hailing from China.

The giant amphibian can be yellowish-brown, reddish-brown, entirely brown, or black, with mottled patterns on its skin. Some are darker than others. Generally found in mountains with rocky, rapidly flowing cold stream with plenty of oxygen, this is where they hide under large rocks along the edge of the water.

The Scientific Classification of the Japanese Giant Salamander

The Japanese giant salamander is of the Animalia Kingdom. Its phylum is Chordata, class is Amphibia, and its order is Urodela. It belongs to the Cryptobrandichae family, in the Andrias Genus. Its species is known as “A. japonicus”, with its binomial name being “Andrias japonicus”, given by Coenraad Jacob Temmick, a Dutch zoologist, in 1837. It is synonymous to the Megalobatrachus japonicus.

The Lifespan of Up to Half A Century

Japanese giant salamanders are nocturnal and take about 5 years to reach maturity.  They also live very long lives. Some giant salamanders have been observed to live longer than 50 years.  

Fully mature Japanese giant salamanders can attain a length of up to 5 feet (that’s the height of one person), while the average weight measured is about 55 pounds. They have an elongated body, two pairs of legs that are roughly the same in size, and a long, broad tail.  They possess tiny eyes that are situated on top of their broad, flat head.  When stressed or threatened, Japanese giant salamanders secrete a sticky white mucus that is toxic to predators. This sticky secretion has earned them the name “big pepper fish” because it smells like Japanese peppers.  

The Japanese giant salamander has smooth skin instead of scales and uses it to breathe carbon dioxide while it's underwater.  It has a single lung that it uses for buoyancy control instead of breathing.  Although almost always submerged in water, this giant salamander can survive on the surface for a long time if its skin is kept moist. 

By Gadow, Hans [Public domain], via Wikimedia Commons

A Keener Sense of Smell

The Japanese giant salamander has very small eyes, which means it can’t see very well. That doesn’t help very much in tracking down prey. These eyes recede into its head as the salamander grows older. 

Although they can’t see too well, they can rely on their sense of smell and touch to find prey, which they catch with a quick sideward snap of the mouth. Teeth on both upper and lower jaws with a second row of teeth on the upper jaw enable the giant salamander to seize the prey in its mouth and bite through bone.  Leading sedentary and solitary lives except during the breeding season, when they mingle in nest sites underwater which are made of long burrows near the river bank.

Instead, it relies on small sensory nodules found on its head and along the sides of its body.  These nodules are like small patches of hair that can detect subtle movements and vibrations in the immediate vicinity, making it acutely aware of the presence of prey or danger. Speaking of danger, this giant salamander has amazing regenerative capabilities.  It can re-grow skin and bones if injured. 

What Does the Japanese Giant Salamander Eat?

Its diet typically consists of fish, shrimp, bugs, crabs, mice, and frogs, although it won’t think twice about dining on other salamanders smaller than them. They can also feed on snakes, turtles and small mammals. Because this salamander is endowed with an extremely slow metabolism, it can go for several weeks with absolutely no feeding.   

Mating Patterns, Reproduction

Breeding season is usually towards late summer, with the female salamander laying about 400 to 500 eggs in autumn.  The male salamanders build dens within the streams, and this is where mating occurs between each gender.

Unlike other salamanders, the female Japanese giant salamanders lay their eggs like a string of pearls held together with a gelatinous material, while the male fertilizes them externally.  Large, heavy males guard the nest sites, eating crabs and newts that might eat the larvae.  They will also attack other giant male salamanders who attempt to fertilize an egg of theirs.

Predators of the Japanese Giant Salamander

The Japanese giant salamander is only usually threatened by other species as they are growing up because they haven’t reached their full size yet. They must go through their biphasic life cycle, so they must survive being larvae and tadpoles. In these stages, their predators are anything from crayfish, other frogs, snakes, birds, to even fish.

Once they reach their full size, the list of possible predators also lessens but still exists. They then must fend off other creatures – animal, and human - from the eggs that they lay, instead of from themselves.

By Momotarou2012 (Own work) [CC BY-SA 3.0 (], via Wikimedia Commons

A Threatened Species, According to the IUCN Red List

Sadly, the Japanese giant salamander is in the “near threatened” category when it comes to their conservation status. It has been on the red list of the International Union for Conservation of Nature, or IUCN. Despite having few competitors in their natural habitats, they do face one creature that endangers them the most – and that creature is the human.

Japanese Giant Salamanders: Not for Sale, Or for Hunting

Because the meat taken from the Japanese giant salamander is used in some special dishes around Asia, it is hunted and sold for profit. Not in Japan, though, as there, they are considered a special natural treasure – which means the government is taking measures to conserve them and is worth more than just a price.

If you’re thinking of keeping one as a pet or to cook and eat, it’s best you think again, and just visit them in a zoo. These salamanders are prohibited from being sought out and internationally traded, as it is stated in CITES, or the Convention of International Trade of Endangered Species. 

Preventing Destruction of their Environment

It isn’t just direct killings that are the cause of their decrease in population. Rivers around Japan are being silted because of heavy deforestation, to make way for more urbanization and development. This ruins their natural habitat, leaving them homeless, and on the brink of death. 

Aside from the pollution that comes with development, even small changes to their living spaces can disorient a Japanese giant salamander. Simple modifications that have been applied over the past century, e.g. placing of bricks on a river to prevent the river from flooding - prevents the salamander from finding a nest to fertilize and defend. This leads them to stray around local villages, to the surprise of its citizens. 

Despite the efforts to keep the population of the Japanese giant salamander going, not much can stop the growth rate of Japan’s human population. So, it is possible to see less of these creatures in the coming years, until their habitats are fully secured. 

Do They Bite?

The Japanese giant salamander is not harmful to humans, though they do secret toxins that will irritate your skin if they feel threatened while you hold them, or try to get a hold of them. They aren’t aggressive like a reptile of that size may be, though they do have the capability to snap off your finger if their mouths ever meet those extremities.

Otherwise, you don’t have to worry about being bitten by a Japanese giant salamander if you’re out for a swim in a river. They are very shy creatures and are likely to avoid human contact as much as possible. 

Public Domain,

The Japanese Giant Salamander in Modern and Traditional Japanese Culture

The Japanese giant salamander has been around so long and enchanted the Japanese so much that if you look at their ancient woodblock paintings (called “ukiyo-e”), you’ll find depictions of these river creatures. One of them was made by a man named Utagawa Kuniyoshi. In the artwork, there is a huge salamander in the water who seems to be grappling with a samurai, as he is in mid-action, stabbing the monster.

Japanese Giant Salamander in Relation to the Kappa

Another indication of the Japanese giant salamander’s effect on Japanese culture back then is the existence of the yokai (monster) “Kappa”. A Kappa is a bipedal imp that has many similarities with the Japanese giant salamander, with a few added magical characteristics. Meaning “river child”, the Kappa has scaly skin that can have different colors; blue, green, and/or yellow. They reek of a fishy smell and are said to have naughty temperaments. Some kappa, though, can be purely evil, snatching and eating children. 

The Kappa could have been based on this amphibian, with the aggressive way it eats its prey. The Japanese giant salamander snaps its head to the side as its powerful jaws snap down on its catch, which may have started fears among townsfolk of the amphibian being dangerous to small children. 

A Japanese Giant Salamander Festival

It’s an understatement to say that the Japanese have a lot of festivals. They have a festival for almost everything, and with such a majestic creature as the Japanese giant salamander in their midst, why not honor its graceful existence it as well?

Every year, on August 8, a celebration is conducted in Okayama Prefecture’s Yubara, which is in Maniwa City. In this neighborhood, it’s not called “Osanshouo”. The locals instead call it “Hanzaki”. This is because the “Han” in “Hanzaki” means “half”, which is connected to the superstition that these salamanders would still grow despite being cut in half.

Two giant floats are displayed during this day, a male Hanzaki, which is dark in color, and a female Hanzaki, which is red. 

As for modern culture, the Japanese giant salamander may have been used as a reference to create the Pokemon “Quagsire”, as they look very much alike, though the Quagsire is colored light blue. There is an article circulating, saying how the Japanese giant salamander is on their list of the world’s ugliest creatures. This does spread awareness about the Japanese giant salamander – albeit in a humorous way. Nevertheless, no matter how ugly some may perceive this creature to be, it sits deep in the hearts of many Japanese.