In early Neocene medium-sized and low-specialized species to reach their full developmental potential. Their offspring exhibit specialization in diverse habitats and diet. One of these species became raccoon dog (Nyctereutes procyonoides). In the forests of the north of Asia, home to its largest carnivorous descendant - a giant tanuka. the Kurilean aglah lives on the Pacific coast of Asia and nearby islands - a descendant of another raccoon dog resembling a fossil of sea bear Kolponomos ( «aglah" - "sea animal" Aleutian).
Kurilean aglah constitution differs considerably from its ancestor. It is a large beast - body length of about 140 cm, tail - up to 60 cm have aglaha massive body, short and almost plantigrade paws with fingers wide apart, connected by the swimming membrane.. The large claws are used for food production and help to cling to the bottom, to resist the waves. This animal swims and dives well, holding the breath for 10 - 12 minutes. This shortened the animal's ears are closed skin folds.
The fur of the animal is thick and velvety gray with lighter spots of irregular shape. The legs and muzzle are darker, brownish; stretches along the back dark brown stripe on the cheeks grow "whiskers" of elongated white wool.
Kurilean aglah feeds on benthic organisms with hard shell - crabs, clams and sea urchins, sea stars eat occasionally and sluggish fish like gobies and flatfish. If aglah catches of seabirds that eat them together with the bones, leaving only feathers from prey. Due to the nature of the diet jaw aglaha very massive and short and chewing muscles are well developed. Molars bladayut thick layer of enamel, and long incisors not stop growing - they begin to wear only in older animals.
Usually aglah looking for crabs and other animals, turning over stones. Underwater animals intended to scare the fish, but prefers to catch those that swim slowly and reluctantly. Also aglah tears from stones and algae adhering to them clams. Among echinoderms aglah preferred species protected by armor or a small number of needles, and obviously avoids Brandt species of sea urchins.
This species lives in small groups consisting of several breeding pairs. Family members care for each other and jointly care for the offspring. Lair of these animals is a hole dug in the ground or a natural shelter among the rocks, which is lined with dry grass and seaweed. The litter is usually 4 - 5 cubs, which are born in the early summer. Newborn cubs are blind and deaf, but are covered with dense hair. Their color - dark gray. During the summer, they reach about half the adult weight and become completely independent in the middle of autumn. Young animals quickly leave their parents and become sexually mature at age one. Life expectancy at this species reaches 12 - 14 years.
To the south, in the Japanese Archipelago and the Korean peninsula close species lives: Japanese aglah (Thalassocanis nipponicus). This animal is smaller: length 150 cm including the tail. This species has a dark color, more like a juvenile coloring Kuril aglaha and the adult animal's head remains black for life. Against this backdrop stand white "whiskers" and a white spot on his chest.
Pacific Coast of North America inhabited Aleutian aglah (Thalassocanis gracilis), featuring a graceful physique and light color - gray with a white patch on the throat and lower jaw. This kind of dark muzzle and black tail tip. Aleutian aglah is weaker jaws and feed on bottom fish and crustaceans moving - shrimp and crabs. On the southern coast of Beringia habitats Aleutian and Kurile aglahov overlap, but these species are not competing due to the difference in diet.