Mustela putorius
The species is very close to the European polecat in general appearance, proportions and habits, though its body seems somewhat more elongated, due to its shorter guard hairs. The tail is short, constituting a third of its body length. The skull is heavier and more massive than that of the European polecat, having more widely spaced zygomatic arches and more strongly developed projections, particularly the sagittal crest. It greatly resembles the black-footed ferret of North America, with the only noticeable differences between them being the steppe polecat's much longer and softer fur, shorter ears, and shorter postmolar extension of the palate. It has four pairs of teats and well-developed anal glands, which can produce a sharp-smelling liquid which is sprayed in self-defence. Males measure 320–562 mm in body length, while females measure 290–520 mm. Tail length of males is 80–183 mm and 290–520 mm for females. Males in Siberia may weigh up to 2,050 grams, while females weigh 1,350 grams. One giant polecat from Semirechye had a body length of about 775 mm. Overall, specimens exhibiting gigantism are more common than in the European polecat, and occur primarily in western Siberia, where they likely hybridise with Siberian weasels.