Paedocypris - This species of fish from Indonesia is the smallest known vertebrate, with adult females measuring just 7.9 mm in length.
Kitti's Hog-Nosed Bat - Also known as the bumblebee bat, this species from Thailand is the world's smallest mammal, with an average length of just 29-33 mm.
Etruscan Shrew - This species of shrew is the smallest known mammal by mass, weighing in at just 1.8 g on average.
Bee Hummingbird - This species of hummingbird from Cuba is the smallest bird in the world, with males measuring just 5.5 cm in length and weighing less than 2 g.
Pygmy Marmoset - This species of monkey from South America is the smallest primate in the world, with adults weighing between 85 and 140 g and measuring just 14-16 cm in length.
Fairyfly - This species of parasitic wasp is the smallest insect in the world, with females measuring just 0.14 mm in length.
Speckled Padloper Tortoise - This species of tortoise from South Africa is the smallest in the world, with adults measuring just 8-10 cm in length and weighing between 95 and 140 g.
Patu Digua - This species of spider from Colombia is the smallest in the world, with males measuring just 0.37 mm in length.
Pygmy Jerboa - This species of rodent from Kazakhstan is the smallest of all jerboas, measuring just 4-5 cm in length.
Stout Infantfish - This species of fish from Australia is the smallest known fish by length, with adults measuring just 7.9 mm in length.