Which is the world's smallest bird?
Smallest organisms been estimated at up to . Nevertheless, sizes of dinosaurs are commonly labelled with a level of uncertainty, as the available material often (or even usually) is incomplete. 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
Smallest organisms "Megaphragma caribea" from Guadeloupe, measuring 170 μm long, is another contender for smallest known insect in the world. Beetles of the tribe Nanosellini are all less than 1 mm long; the smallest confirmed specimen is of "Scydosella musawasensis" at 325 μm long; a few other nanosellines are reportedly smaller, in historical literature, but none of these records have been confirmed using accurate modern tools. These are among the tiniest non-parasitic insects. The western pygmy blue ("Brephidium exilis") is one of the smallest butterflies in the world. The smallest sea cucumber, and also the smallest echinoderm, is "Psammothuria ganapati", a synaptid