Species is part of the classification of living organisms. A species is a group of individuals that (1) actually or potentially interbreed with each other but not with other such groups, (2) show continuous morphological variations within the group but which is distinct from other such groups. Taxonomically, species are grouped into genera and divided into subspecies and varieties. Each species has a unique two-part Latin name, the first part being the genus name. For example, the tiger's species name is Panthera tigris, Panthera being the genus of the big cats. So far, more than 1.5 million plant and animal species have been identified, but estimates of the total number on land and in the ocean run as high as 100 million.