Zarigani
Encyclopedia
Zarigani is a species of crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...

 endemic
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...

 to Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

.

It is small in size (6 cm) and grayish in color. Its front claws are much weaker than those of other crayfish. Zarigani need low temperature and high water purity, so they live in upper streams of rivers or lakes in highland regions. The distribution of zarigani comprises Hokkaidō
Hokkaido
, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island; it is also the largest and northernmost of Japan's 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaido from Honshu, although the two islands are connected by the underwater railway Seikan Tunnel...

 and northern Tōhoku
Tohoku region
The is a geographical area of Japan. The region occupies the northeastern portion of Honshu, the largest island of Japan. The region consists of six prefectures : Akita, Aomori, Fukushima, Iwate, Miyagi and Yamagata....

 (the northern area of Honshū
Honshu
is the largest island of Japan. The nation's main island, it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait...

).

The Environmental Agency (now Ministry of Environment) of Japan added it as a vulnerable species (IUCN
World Conservation Union
The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...

 category) to the Red Data List in 2000. It is thought that the causes of its decrease are corruption of water quality and the spread of the American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 crayfish Pacifastacus leniusculus, which was imported in the 20th century and has steadily proliferated in northern Japan. Some suspect that this American crayfish carries some disease, such as the crayfish plague
Crayfish plague
Crayfish plague, Aphanomyces astaci, is a water mould that infects crayfish, most notably the European Astacus which dies within a few weeks of being infected...

known in Europe, that eliminates zarigani.
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