River Monsters from Myth to Reality: Japan’s Giant Salamander

What to know about Japanese Giant Salamanders?

The Discovery of the Giant Salamander

Japanese giant salamanders are amphibians that live in the rivers of Japan. According to science, these species of salamanders may have originated from the same ancestor as the Chinese giant salamander and the eastern hellbender. There is very minimal information about these organisms but what is known about them is the fact that they are also known as Japanese pepper fish. This is because of the fact that they excrete smells that are similar to that of a Japanese pepper plant.

It was in the 1820s when the discovery and the first ever recording of the Japanese giant salamander was done. The first set of giant salamanders was found in the Dejima Island of Nagasaki by a man named Philipp Franz von Siebold. At this time, it was shipped to Netherlands for study. More than a century later, the Japanese giant salamander was considered as a special natural monument forcing the government to protect these creatures against poachers.

The Japanese Giant Salamander may be one of the ugliest creatures on earth, but they surely are one of the gentlest. There had been minimal records of salamanders hurting humans. If not, it is the humans that cause danger to these creatures.

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

The Importance of the giant salamander  to the Japanese Culture

Through history, the Japanese giant salamander was only part of legends and myths. Some experts say that the Japanese giant salamander is the inspiration behind the mythological creature known as the kappa. This is an imp or a demon that live in the rivers of Japan. The only difference is that the kappa is humanoid in form, a half human half amphibian that is a size of a child.

These kinds of creatures, along with gigantic snakes, and tiny dragons are usually depicted in ancient Japanese art. There are indications that the Japanese giant salamander is the inspiration for all of this. There are a number of artworks that depict large salamanders being combatted by mighty samurai. To celebrate these creatures, there is a Giant Salamander festival held August of every year in Minawa City, Japan. This is to celebrate and give honor to these wonderful creatures.

The Japanese Giant Salamander Habitat

These kinds of animals cannot be found in international soils. They are usually exclusive to South East Asia. They live in freshwater rivers all their life and just go up the streams to breed. They are found to like clear and cool waters. What is even more special about these organisms is that they are nocturnal. This means that they are looking for prey mostly at night.

They usually found in waters as deep as 1,350 meters. They like very cold streams and rivers. Every now and then, they go to the streams with shallow water to breed. Also, these places provide enough oxygen to their skin allowing these organisms to stay long underwater.

Most species of the Japanese giant salamander can be found in the northern regions of Japan’s Kyushu Island. Some species are also found in the Western Honshu Island in Japan.

Japanese Giant Salamander Size, color, and shape

The size of a Japanese giant salamander extends to about 1.5 m or five feet in length, making it the second-largest in the world. They have an interesting flattened head, which is what it is best known for. They have very small eyes and leathery yet slimy skin. Since their eyes are quite small, they have very impaired vision. The giant salamander can grow up to about 55 pounds on average which makes them comparatively heavy as a three-year-old child.

Giant salamanders are usually colored to mimic the surrounding rocks as a form of their protection. Normally, these salamanders are colored yellowish-brown and reddish-brown. Sometimes, these salamanders become brown or black entirely. They have an interesting pattern of spots and splotches around their leathery skin.

Japanese Giant Salamander Life Span

Since these species of creatures are usually found in the deep, there is no specific data to state the average life span of a Japanese Giant Salamander. However, the longest a giant salamander lived in captivity was 52 years. Some research indicates that in the wild these kinds of animals can live as long as 80 years of age.

Usually, a Japanese giant salamander has three stages of development The first stage involves the formation of the embryo once the female salamander lays them. The second is the hatching of the eggs that happens about 12 to 15 weeks after fertilization. The last stage will be the adult stage which most scientists believe is an incomplete metamorphosis. This is because of the fact that they do not develop eyelids and retain gill slits in their neck. Furthermore, they do not develop their teeth any further. They also develop lungs, which they never use.

Sustaining the population of Japanese Giant Salamanders

Japanese Giant Salamander Reproduction

The mating season of Japanese Giant Salamanders usually happens during the late summers of August of every year. Female salamanders usually lay their eggs at the earlier parts of autumn making a female salamander capable of laying eggs at a rating of only once every year. During the mating season, male salamanders usually go to occupy burrows in the streams. Usually, they are located not too deep into the water. These ‘dens’ are usually where breeding and nesting happens.  These male salamanders usually closely guard these dens until female salamanders enter. Once the male and female salamanders have mated, the female salamander will leave two strings of fertilized eggs. Then the male salamander will closely guard the den until the eggs are hatched.


What is interesting about Japanese giant salamanders are known for the way they take care of their young. Unlike other amphibians in the world, male giant salamanders take really good care of their offspring which is quite unusual. But what is more unusual is the fact that the female salamanders play no part after the laying of the fertilized eggs.

To help in the process of reproduction, these male salamanders take really good care of the eggs. The first thing they do is to provide oxygen to the eggs through what is scientifically known as tail-fanning. After that, male salamanders will help in the development of embryos through agitating them with the use of their heads and bodies. Through this process as well, they ensure that the eggs are guarded against small predators.

 Lastly, although this part is quite unusual, male salamanders eat their eggs. According to research, they do this to eggs that are the whitest out of the bunch. Eggs that are of this color are usually unfertilized and may contain water molds which could infect the other eggs.

Japanese Giant Salamander Eggs

For every time a female salamander lays an egg, there are about two strings of it that total to about 600 eggs. The problem with this is that not all of it will actually survive. Some are laid unfertilized while others have died due to infection from water molds. To ensure that the other eggs are not infected, the male salamanders will eat up dead eggs.

Healthy eggs, on the other hand, can measure about 4 mm to 6 mm and are mostly just a healthy yellow color. This is how the male salamander determines if their young are healthy.

Can we keep Japanese Giant Salamanders as pets?

Since it is considered as a natural monument, keeping one as a pet is strictly not allowed. Because of their endangered status, these organisms are strongly protected by the law. Only recognized and accredited agencies can take these organisms to captivity and take care of them. Furthermore, because of their habitat requirements taking care of a Japanese giant salamander is never easy.

Japanese Giant Salamanders Eating

These kinds of organisms are well noted for their carnivorous diet. They have tiny teeth so they usually just suck their prey into their mouth. They are known to not have any saliva.

Japanese giant salamanders actually don’t use their eyes for stalking prey. Their head and their body are equipped with small sensory nodules, similar to a taste bud that can detect prey in the surroundings. These nodes use very subtle vibrations that send a message to the salamander that there is another creature within the area.

Mostly, these kinds of salamanders eat up bugs, crabs, fishes, and frogs. There are also some cases when they eat mice when they are found in shallower parts of the river. Sometimes, larger adult salamanders eat up smaller salamanders depending on the abundance of other food.

What is interesting about these species of creatures is that they have a very slow metabolism. This means that they can survive with very little sustenance. In fact, they can survive for weeks without ingesting any food.

Are Japanese Giant Salamanders river monsters?

Although they are depicted as demonic organisms in historical Japan, these creatures are actually quite gentle. They are a slow moving organism which sleeps during the day. These organisms don’t go up to the surface and stay at the bottoms of streams even when moving.

The problem with these organisms is that the male salamanders are highly territorial, but only to potential predators and competition. During the mating season, large male salamanders can kill smaller competition that tries to go into their burrows or dens in hopes of stealing another male salamander’s young.

Regardless of their status in culture, these organisms actually play a negative role in the ecosystem. They are known to be hosts for parasites such as roundworms. Furthermore, since these organisms usually feed on small fish a number of fishermen are afraid that the presence of giant salamanders in their rivers will significantly affect the number of fish that they can catch and sell. Other than these roles they play in the ecosystem, these organisms are not really monsters as the legends make them be.

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

The Life and Death of Giant Salamanders

Japanese Giant Salamanders are endangered

These species of creatures are actually included in the world’s endangered list since 2004. There had been conversations on how to save these creatures from extinction. They are not poached so the source of their dwindling number is actually from their habitats. Because of the presence of dams in large rivers, the natural habitat of these kinds of creatures is strongly affected. There are some streams that have lost water due to streams. Without this, giant salamanders cannot properly mate and reproduce.

Nowadays, there is an extensive research on how to help these organisms increase their reproduction. Scientists and zoologists have found ways to create artificial burrows that male salamanders can turn into mating dens. So far, there has been some success but it is still unsure if all giant salamanders will adjust and adapt to the changes.

Since its endangered status was reported in 2004, there had been a number of organizations that work their way to ensuring that these animals continue to breed. The Asa Zoo of Japan is one of the most important organizations to the lives of the Japanese giant salamander. They are the first organization to successfully breed these salamanders in captivity. They have created artificial dens and habitats for these organisms.

Japanese Giant Salamander predators

Another interesting fact about these giant salamanders is the fact that they lack natural competitors. Since they live in rivers with not many large organisms other than themselves, they are pretty much protected when it comes to food even if they can survive long without eating. Other than that, their interestingly designed skin blends so well with its habitat that it is well protected against predators.

What is more in danger are their eggs. Fishes and other small insects are the usual main predators of their eggs. This is why male salamanders are always on a close lookout for the potential danger that could harm their young.

The worst predators that may endanger the lives of these organisms would be humans. Some parts of Asia still hunt these salamanders for food. Furthermore, most oriental medicine use parts of these animals in traditional medicine practices.