Zosterops (meaning "eye-girdle") is a genus of passerine birds containing the typical white-eyes in the white-eye family Zosteropidae. The genus has the largest number of species in the white-eye family. They occur in the Afrotropical, Indomalayan, and Australasian realms. Typical white-eyes have a length of between 8 and 15 cm (3 and 6 in). Their most characteristic feature is a conspicuous white feather ring around the eye, though some species lack it. The species in this group vary in the structural adaptations of the tongue. The Zosterops [griseotinctus] group is an example of a "great speciator" inhabiting a vast area and showing a remarkable morphological differentiation on islands, some of which maybe as close as 2 km (1.2 mi) apart.