The most famous and beloved animal, the Japanese river otter

The Japanese river otter (Lutra lutra whiteleyi) was in former times quite common in Japan and dating back to 1880, it was even seen in Tokyo. But since the Meji time the species was overhunted and the population suddenly shrank in the 1930s. Between 1955 and 1959 the otter was seen on Honshu, Kyushu and Hokkaido for the last time. Afterwards it has only been spotted a few times, in 1964 in the Seto Inland Sea and in the Uwa Sea in 1972 and 1973.

Stuffed Japanese river otter@Tobe Zoo(Click to view larger image).

Skeleton of Japanese river otter@Tokyo NH museum(Click to view larger image).

The last official sighting of a Japanese river otter was on the southern Shikoku in 1979, when it was photographed in the mouth of the Shinjo River in Susaki. Also in 1979 a dead animal was found on Shikoku. This was apparently the last specimen of its kind. Since 1979, many expeditions to the otter’s former distribution tried to find a sign of the otter’s existence. But all these expeditions and attempts failed. Therefore on August 28, 2012 the Japanese Ministry for Environment declared officially the Japanese otter as extinct.

We are very proud that our LOST ZOO is now the first institution which keeps this rare animal since almost 40 years again. - The Japanese river otter is 65-80 cm long and has a tail measuring 45-50 cm. It is more active at night than during daytime. After dark, the Japanese river otter leaves its den to forage for food. Primarily it feeds on fish, crab, and shrimp, but likes also beetles, watermelons, and sweet potatoes. Many Japanese river otters eat about 15% to 25% of their own body weight and in nature they spend around six hours to find food because of their difficult living space and their competition for food. Therefore their territory is about 15 kilometres in diameter. The otter marks its home range with its droppings about one to three miles apart and sets up three or four nests under rocks or inside bushes. The otter is always on the move, visiting each den only once every 3-4 days.

With an age of 2-3 years, Japanese River Otter are mature and will start to reproduce. Besides during reproduction and with the exception of young males staying with their mother for a range of 2-3 years until they are mature, female otters and male otters don’t live together. The Japanese river otter can have 1-6 cubs per litter. Once born, the baby otters are completely blind for a month, leaving them absolutely helpless during this time. Only the female is looking for the babies, nursing them for up to eight hours a day, as well as teaching them lessons and protecting them. With an age of 4 months, the youngsters will start to feed solid food and to hunt.

Old painting of Japanese river otter(Click to view larger image).

The Japanese river otter was in the past and is even today very popular, because it provided with many stories. It is the model of an imaginary animal “Kappa”, a mixture of otter, monkey, turtle, frog and human. The otter was the fearful model of the “Kappa” in the 16thcentury. The monkey-type became the mainstream in the 17thcentury, the human-type in the 18thcentury and the turtle-type went to extinction in the 19thcentury. But the “Kappa” is still surviving until today in a comical and manga form.

But our LOST ZOO keeps now live Japanese river otters, which have a thick, lush coat of dark brown fur and short webbed feet. The scientists still debate, if the Japanese river otter is a subspecies of the Eurasian river otter or if it is a separate species. The Japanese form is definitely larger than most of the subspecies of the other Eurasian river otter. On the other hand the Korean and Chinese river otters are even still larger. Besides there is also a genetic difference to the Korean river otter, therefore many scientists see the Japanese river otter today as a special species Lutra nippon.

Executive Curator
JURGEN LANGE