An endemic (from the Greek ἔνδημος ‘local’) is an animal or plant that lives within a limited space and is unique to a single territory. The emergence of endemics is usually due to geographical isolation. More often than not, endemics are found on oceanic islands. Particularly famous geographically unique species are Australian kangaroos, platypus and koalas (fauna); sequoia, obregonia and pachyderms (flora).
All geographically unique species are divided into palaeoendemics (species which are on the verge of extinction) and neoendemics (species which appeared within a limited space relatively recently). But there is also a third group: highly endemic species or species which are found in even more restricted area, say, a valley or a desert.
The percentage of endemics among all species of any flora or fauna is a direct indicator of their uniqueness. Plants endemics of Saint Helena (Atlantic Ocean) account for more than 80% of all inhabitants. For example, some species of cabbage trees grow in this area alone. Approximately 70% of the endemics are concentrated in the range of Lake Baikal. Endemics of the Siberian lake include Baikal omul, epishura, and seal.