USA, Oita Prefecture--Home to Kyushu’s only natural habitat of the Japanese giant salamander, officials here are offering the public a real-life 3-D look at the elusive amphibian species.

The Usa city government commissioned the making of digital models of the body of a dead Japanese giant salamander discovered in an irrigation channel in the Innaimachi district of Usa in 2018.

It has posted the 3-D models for public access on its website. 

The models, which allow the viewer to glance into every nook and corner of the salamander’s body, including its skeleton and internal organs, are the first of its type to be made public in Japan, officials said.

Yokohama-based JMC Corp. made the digital models at the request of Usa officials on the basis of the 73-centimeter-long specimen, which had been preserved in a freezer. 

The 3-D digital modeling process involves the use of a computer tomography (CT) scanner to irradiate the subject with X-rays to visualize its internal structure and other features, which are then reproduced graphically.

On exhibit are a 3-D model of the outward appearance, a 3-D model of the skeleton and tomographic imagery of the internal structure.

The Usa city government decided to have the 3-D models made for the purpose of education and research as the central government has designated the Japanese giant salamander as a special natural monument.

The Yakkangawa river system in the Innaimachi district of Usa contains one of Japan’s rare habitats of this salamander species. Starting in 2000, the city government here has been microchipping individuals of the species--there are 420 of them now--for the purpose of protection.

“Perhaps double that number are actually living,” an official with the social education division of the Usa municipal board of education said.

The Agency for Cultural Affairs has recommended that specimens of the Japanese giant salamander, which are cultural assets, should be used as teaching aids, according to officials of the social education division.

The 3-D modeling work showed, for example, that the salamander’s digestive tract retained undigested items, including claws of a crustacean and bones of a frog, and that the animal had a bone fracture in its lower jaw.

The salamander also has a multitude of pointed teeth, called the vomerine teeth, which is evidence of the amphibian’s “high preying capabilities,” the officials said.

Japanese giant salamanders and other large amphibians are difficult to dissect and make into specimens, so it is rare for the skeletal structure and other features to be elucidated in such detail, the officials added.

The 3-D digital models “will be useful, among other things, for future research and in giving treatment to individual salamanders,” one expert said.

The municipal board of education is planning in the future to use the 3-D models to teach elementary school pupils about the ecology of Japanese giant salamanders. It also plans to organize a session at a roadside rest area for taking a close look at the 3-D digital models.

“I hope spreading interest in this rare creature called the Japanese giant salamander will help people become more aware that they should take good care of the environment, including rivers,” the official said.

The 3-D digital models can be viewed on the Usa city government website and on “CT Seibutsu Zukan” (CT picture book of creatures), a JMC website.

HIGH SCHOOLERS MAKE RELIEF MODEL

The 3-D data for the digital models were used by students of Usa Industrial Science High School in Usa in creating relief models of the Japanese giant salamander.

A life-size relief model is on display at “Japan’s biodiversity and its preservation,” an exhibition running at the Oita Prefectural Art Museum in the prefectural capital of Oita from Aug. 8 through Oct. 18.

Reconstruction of the model was requested by the city government.

It took some 20 students, including from the high school’s robotics department, four days to make a prototype model in three parts--the head, the trunk and the tail--by using a 3-D printer and other tools.

The students faithfully reproduced details of the animal, including its skin texture and minuscule teeth.

Members of the high school’s art club helped with the coloring of a separate model for display.

“I feel so proud that a model of our making will be exhibited at a public venue,” said Shunjiro Takahashi, 18, a third-year student, before the start of the exhibition.