The mustelidae is the largest and most diverse family of the Carnivora. The family is unified by an ancestral long-thin body plan, and the physical, physiological and ecological consequences this has for them. Yet within the family, even within species, life history patterns can be surprisingly variable. From the world’s smallest carnivore, the Weasel (Mustela nivalis), the family ranges almost a thousand-fold in weight to the Sea Otter (Enhydra lutris). Whereas Stoats (Mustela ermine)rank among the most numerous of carnivores and are common throughout the northern Holarctic, Black-footed Ferrets (M. nigripes)live at the brink of extinction, supported only by high-profile reintroductions.