Smallest organisms
With a mass of approximately and a length of 5 centimetres (2.0 in), the bee hummingbird ("Mellisuga helenae") is the world's smallest bird species and the smallest warm-blooded vertebrate. Called the "zunzún" in its native habitat on Cuba, it is lighter than a Canadian or U.S. penny. It is said that it is "more apt to be mistaken for a bee than a bird". The bee hummingbird eats half its total body mass and drinks eight times its total body mass each day. Its nest is 3 cm across.
Tiny sunbird
The tiny sunbird is the smallest species in the genus. The adult male has a metallic green head, back and throat, dark brown wings, a metallic blue rump and a black tail with a purplish-blue sheen. It has a narrow blue breast band above a wider scarlet breast band, lemon-yellow pectoral tufts and a dark olive belly. The adult female has an olive-brown head and upper parts, dark brown wings and dark brown tail. There is an olive-yellow supercilium over the eye, the throat is grey and the underparts are olive washed with yellow. The eyes in both sexes are dark brown and the beak and legs are black. The juvenile resembles the female.