Encounter a Rare Species: The Japanese Giant Salamander
What is a hanzaki?
Hanzaki is the regional name for the Japanese giant salamander (Andrias japonicus), a species endemic to Japan. Like its two cousins in China and North America, this fully aquatic amphibian is a living fossil, largely unchanged over millions of years of evolution.
In standard Japanese, this amphibian is called an о̄sanshо̄uo: о̄ meaning “giant,” and sanshо̄uo being the generic name for a salamander. The name of hanzaki, however, means “torn in half” and refers to the giant salamander’s ability to regenerate severed limbs—support for the folk belief that it could even survive being cut in half.
Together with its Chinese counterpart, the Japanese giant salamander represents the world’s largest extant salamander species. It achieves adulthood at an age of 15 to 20 years, and can grow up to 150 centimeters in length and 35 kilograms in weight. Its lifespan can reach 70 years or more.
Hanzaki have small eyes toward the front of their heads. While it is unclear how well they can see, they can track motion and are likely to snap up anything that moves close to their mouths. As a result, they are indiscriminate eaters and will snag crabs, fish, other amphibians, insects, and even small mammals with the help of their widely hinged jaws and small, sharp teeth. Like most salamanders, hanzaki are born with gills, but begin losing them at around three years of age. After that, they absorb oxygen through their skin, aided by the loose folds along their sides that increase its surface area. For this reason they depend on clear, fast-moving water that circulates sufficient oxygen for them to breathe.
Japanese giant salamanders live in rivers and streams with gravel bottoms, concealing themselves in caverns or burrows along the edge. These also serve as mating dens, each guarded by a single male who hopes to attract females to spawn in his domain. Once eggs are laid—typically from late-August to mid-September—this “den master” releases sperm to fertilize them, and will then spend the next six months guarding the eggs and the larvae that hatch from them.
Sadly, human activities such as damming and concrete riverbank reinforcement have destroyed or severely fragmented much of the hanzaki’s habitat. The 2020 edition of the Red List, an indicator of extinction risk maintained by the Ministry of the Environment, elevated the status of the Japanese giant salamander from Near Threatened (NT) to Vulnerable (VU).
Hanzaki in Local Culture
A local folktale tells how a 10-meter-long hanzaki was troubling a village by gobbling up livestock and people who wandered too close. The villagers offered a reward to anyone who killed the monster, and a man called Hikoshirō volunteered. He jumped into the water with knife clenched in his teeth. The hanzaki promptly swallowed him whole, but Hikoshirō cut himself free from the inside, apparently killing the beast. From that day forward, however, Hikoshirō’s home was haunted by strange noises—then he and his entire family mysteriously died. The villagers built a shrine to pacify the vengeful hanzaki, giving him the deific name Hanzaki Daimyōjin.
Every year on August 8, the town of Yubara holds a Hanzaki Festival to honor this unique deity. Two giant floats topped with hanzaki figures, a reddish-hued female and a darker-skinned male, are paraded through the streets to the accompaniment of dancing and live music. After dark, a hanzaki-shaped lantern float joins the revelry before the festival concludes with fireworks.
Seeing a Hanzaki
Spotting the reclusive hanzaki in the wild can be difficult, but visitors to Maniwa can see this protected species at the Hanzaki Center, a research and conservation facility founded in 1971. Living at the Center are a multitude of hanzaki in all stages of development, from embryos in eggs to fully grown adults. The facility also holds a record-pushing preserved adult measuring 150 centimeters in length and more than 30 kilograms in weight. From the Center’s exhibits, visitors can learn about the natural habitat of this rare animal, how it has figured in local lore, and the ongoing conservation efforts on its behalf.