Fauna of the Kuril Islands

The sea otter (Enhydra lutris) is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between 14 and 45 kg (30 and 100 lb), making them the heaviest members of the weasel family, but among the smallest marine mammals. Unlike most marine mammals, the sea otter's primary form of insulation is an exceptionally thick coat of fur, the densest in the animal kingdom. Although it can walk on land, the sea otter is capable of living exclusively in the ocean.

Aquatica lateralis, known as "heike-botaru" (ヘイケボタル) in Japanese, is a species of firefly found in Russia, Japan and Korea. It was formerly placed in the genus Luciola. The larvae are aquatic and live in rice paddies.

The Far Eastern smooth flounder (Liopsetta pinnifasciata) is a flatfish of the family Pleuronectidae. It is a demersal fish that lives on bottoms in salt, brackish and fresh waters. Its native habitat is the temperate waters of the northwestern Pacific, specifically Japan, Russia and the Kuril Islands. It can grow up to 50 centimetres (20 in) in length.

The blackfin flounder (Glyptocephalus stelleri) is a flatfish of the family Pleuronectidae. It is a demersal fish that lives in temperate waters at depths of between 8 and 1,600 metres (26 and 5,249 ft), though it is most commonly found between 15 and 800 metres (49 and 2,625 ft). Its native habitat is the northern Pacific, from the Sea of Japan to the Strait of Tartary and southern Kuril Islands and out into the Bering Sea. It grows up to 52 centimetres (20 in) in length, and can weigh up to 1.5 kilograms (3.3 lb). Maximum reported lifespan is 23 years.

The Kamchatka brown bear (Ursus arctos beringianus), also known as the Far Eastern brown bear, or in Russian: камчатский бурый медведь, kamchatsky bury medved, is a subspecies of brown bear native to the Russian Kamchatka Peninsula.

The Hokkaido wolf (Canis lupus hattai), also known as the Ezo wolf (Japanese: エゾオオカミ（蝦夷狼）ー, Hepburn: Ezo Ōkami) and in Russia as the Sakhalin wolf, is an extinct subspecies of gray wolf that once inhabited coastal northeast Asia. Its nearest relatives were the wolves of North America rather than Asia. It was exterminated in Hokkaido during the Meiji Restoration period, when American-style agricultural reforms incorporated the use of strychnine-laced baits to kill livestock predators. Some taxonomists believe that it survived up until 1945 on the island of Sakhalin. It was one of two subspecies that were once found in the Japanese archipelago, the other being the Japanese wolf (C. l. hodophilax).

The speckled flounder (Limanda punctatissima) is a flatfish of the family Pleuronectidae. It is a demersal fish that lives on bottoms in the temperate waters of the northwestern Pacific, from the southern Sea of Okhotsk and the Kuril Islands to the Sea of Japan, including coastal areas of Japan and Korea. It can grow up to 40 centimetres (16 in) in length, and can weigh up to 450 grams (16 oz).

Maiestas variegata (formerly Recilia variegata) is a species of insect from the Cicadellidae family that is endemic to Kuril Islands. It was formerly placed within Recilia, but a 2009 revision moved it to Maiestas.

Tythothyris is a monotypic genus of brachiopods belonging to the family Terebrataliidae. The only species is Tythothyris rosimarginata.