Japanese Giant Salamander: A Mascot of Edo Period Japan

In the wet, dark corners of Japanese forests, where streams create deep gorges, fortunate visitors may come across one of the country's most famous creatures: the giant salamander, also known as Hynobius japonicus.

The striking coloration of many salamanders living in Japan serves as a warning to predators about its toxic skin

Japan is home to 44 different species of salamanders, ranging from small to large and new ones are still being discovered

One type of Japanese salamander, known as the "flowing water" salamander, lives in mountain streams. These salamanders lay their eggs on the stones in the stream. Their habitat is far from human settlements, featuring steep slopes and dangers like falls and falling rocks, making these areas accessible only to experienced individuals. As a result, the encounter of humans with them is very rare and some species' ecology, such as the red-spotted salamander, still needs to be better understood.

In contrast, the "static water" salamanders reside in low mountain areas. They lay their eggs in the slow-moving waters such as ponds, puddles, and rice fields.

A salamander is a unique cold-blooded animal

Typically, reptiles such as snakes, lizards, and turtles, as well as amphibians like frogs and newts, become active in warmer temperatures and hibernate when it gets cold. They seek refuge in the soil or muddy water during winter. Consequently, their habitats are primarily in tropical, subtropical, and temperate regions.

The Japanese Giant Salamander is among the world's longest-living aquatic animals, living for over 50 years

However, most salamanders, do not hibernate. Even in subzero conditions, their activity merely slows down, but they do not enter a state of suspended animation. They are real cold-blooded animals.

As true cold-blooded amphibian, salamander is highly sensitive to high temperatures. Before touching salamander (which should be avoided), it's essential to lower your body temperature. You can do this by dipping your hands in cold water or wearing gloves made of a material that doesn't transfer heat.

To put it into perspective, the temperature difference between a human palm and a salamander's body can exceed 30 degrees Celsius. This is akin to human skin being suddenly exposed to hot water over 60 degrees Celsius.

The World Largest Amphibian

Unlike the fire salamander found in Europe, the Japanese giant salamander has a more basic appearance, sporting smooth, glossy skin in shades of dark brown or black. Likewise, its skin cannot emit light in the dark as the skin of the Eastern tiger salamander. Its body ends with a pointed tail which is essential for swimming.

The giant salamander has an average length of 60cm. In the past, specimens measuring up to 148cm in length and weighing 30kg were observed. Yet, it appears that because of changes in its environment, like the building of dams and straightening of the river courses, bigger specimens are no longer seen.

Despite having lungs, Japanese Giant Salamanders mainly absorb oxygen through their skin

During the day, it hides behind logs and rocks and come out at night to hunt. Though mostly nocturnal, Japanese salamanders sometimes venture out during the day, especially in cases of heavy rain or very high humidity. As can be seen in the following video.

Dwelling Places of Giant Salamander in Forest

In June, female salamanders travel upstream and lay eggs under rocks in mountain streams. The eggs undergo various stages before reaching maturity through a process known as metamorphosis. 

Japanese giant salamanders are native to the cool, fast-flowing streams and rivers of Japan

Giant salamander, do not maintain any kind of permanent dwelling. It prefers to live in rock crevices filled with gentle currents or holes formed by tree roots, where it usually lives alone.

In contrast, their breeding burrows are horizontal holes dug in shallow water about 20 cm deep, wide enough for a giant salamander to pass through, with a spacious round area at the back. While they sometimes also use natural underwater caves, giant salamanders often dig their breeding rooms.

Japanese Giant Salamander in Edo Period Japan

In the Edo period, the giant salamander was considered a "kaibutsu" (怪物) like mythical creatures such as tengu and kappa.

Due to its rarity, the giant salamander was often connected with purely mythological creatures such as kappa

In popular imagination, Giant Salamander could live for centuries and regenerate if cut in half.

One famous story about it involves the Kamo Shrine in Kyoto. According to the story, a giant salamander once appeared near the shrine, causing a commotion among the monks. Monks never saw something like this before and thought it is the legendary kappa.

The temple abbot, understanding its sacred importance, ordered to capture the animal and put it in a pond. Unfortunately, the salamander soon died because the crystal-clear water of a pond without vegetation did not provide what it needed.

Some parts of giant salamanders were used in traditional Japanese medicine

The medical book "Honchō Shokkan" (本朝食鑑) from the Edo period, written by Hitomi Hitsudai, discusses the application of giant salamander oil for treating wounds, skin ailments, and asthma. The oil from giant salamanders was thought to possess powerful anti-inflammatory characteristics that helped decrease swelling. The manual also suggested using the oil for respiratory problems, as breathing in its vapors was believed to help open the air passages and improve breathing.

Regrettably, the Japanese giant salamander was also consumed. The "Ryori Monogatari" from the Edo period, dating back to approximately 1643, includes salamanders as a listed ingredient in its cooking recipes. The book states that the giant salamander meat is tough but becomes soft after being simmered for an extended period. It has the same flavor as soft-shelled turtle meat but lacks the unpleasant smell. 

Luckily, the big salamander never became a common element in Japanese cooking and so it was not in danger of disappearing. That changed in the 20th century.

The Japanese giant salamander is endangered by industrialization

Currently, the Japanese giant salamander is at risk of becoming extinct.

In the last fifty years, industrialization has posed a significant threat. Channelization is employed to modify the natural form of rivers to meet the increasing needs of the industry. Man-made intervention in the form of straightening or changing the natural shape of rivers with concrete has removed necessary habitats for aquatic creatures, such as rocks, holes, roots, and crevices along the riverbanks essential for their survival.

Moreover, dams and man-made cascades alter the natural flow of water, impacting factors such as temperature, sediment transport, and nutrient levels in the water.

 

Channelizing Japan's rivers with concrete in recent decades harmed salamander habitats

The pollution caused by industries, agriculture, and urban waste has a harmful effect on aquatic animals that are vulnerable to changes in water quality. Several species are currently facing infertility as a result of toxins and pollutants being introduced into the rivers. Efforts towards complete protection are required to address all of these threats.

The preservation of the iconic Japanese salamander is a matter of great significance for the nation.

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