The smallest organism found on Earth can be measured using a variety of different methods, and can be defined as the smallest by volume, mass, height, or length
Smallest Amphibian: Monte Iberia Eleuth; Brazilian Gold Frog
The Brazilian Gold Frog (Brachycephalus didactylus), also known as Izecksohn's Toad, is the smallest frog in the Southern Hemisphere. It was previously called Psyllophryne didactyla
At just over 3/8 inches (9.6 - 9.8 mm) long, the Monte Iberia Eleuth (Eleutherodactylus iberia) is the smallest living frog in the northern hemisphere. It is the second-smallest frog (and tetrapod) in the world, following the Brazilian Gold Frog.
Smallest Reptile: Jaragua Sphaero; Virgin Gorda Least Gecko
The Jaragua Sphaero, or dwarf gecko, measures three-fourths of an inch from nose to tail tip and weighs just 0.00455 of an ounce (by contrast, the largest animal, the blue whale, is 1,600 times longer and more than 1 billion times heavier)
Its range is believed to be limited to Jaragua National Park in the extreme southwest of the Dominican Republic and the nearby forested Beata Island
Sphaerodactylus parthenopion or "Virgin Gorda Least Gecko," which was discovered in 1965 in the British Virgin Islands.Range about sixteen millimeters long as an adult from nose to tail.
Smallest Mammal: Kitti’s Hog-nosed Bat
Kitti's Hog-nosed Bat (Craseonycteris thonglongyai), also known as the bumblebee bat, is a vulnerable species of bat and the only member of the family Craseonycteridae. It occurs in western Thailand and southeast Burma, where it occupies limestone caves along rivers.
Kitti's Hog-nosed Bat is the smallest species of bat and one of the world's smallest mammals. It has a reddish-brown or grey coat, with a distinctive pig-like snout. Colonies range greatly in size, with an average of 100 individuals per cave. The bat feeds during short activity periods in the evening and dawn, foraging around nearby forest areas for insects. Females give birth annually to a single offspring.
Kitti's Hog-nosed Bat is about 29–33 millimetres (1.14–1.30 in) in length and 2 grams (0.07 oz) in mass), hence the common name of "bumblebee bat".
Smallest Insect: Dicopomorpha Echmepterygis
The parasitic wasp known as Dicopomorpha echmepterygis measures 139 ?m, or a little over a tenth of a millimeter. Males of the species are blind and wingless, but females are capable of flight.
Smallest Turtle: Speckled Padloper Tortoise
The Speckled padloper tortoise (Homopus signatus) is the world's smallest tortoise. Found in western South Africa, the males measure 6-8 cm (2.3-3.1 in), while females measure up to almost 10 cm (4 in). It feeds on small succulent plants.
Smallest Bird: Bee Hummingbird
The Bee Hummingbird or Zunzuncito (Mellisuga helenae) is a species of hummingbird that is endemic to Cuba and Isla de la Juventud. With a mass of approximately 1.8 grams (0.063 oz) and a length of 5 centimetres (2.0 in), it is the smallest bird.
Smallest Crocodilian: Cuvier’s Dwarf Caiman
The Cuvier's Dwarf Caiman or Musky Caiman, Paleosuchus palpebrosus, is a relatively small crocodilian reptile from northern and central South America. It is found in Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Surinam and Venezuela. It lives primarily near fast stretches of stream, but also in nutrient-deficient waters.
With a total length of up to 1.6 m (5.2 ft) in males and typically up to 1.2m (4 ft) in females, it is the smallest extant species of crocodilian. Juvenile dwarf caimans eat invertebrates, while adult caimans eat both fish and invertebrates. It uses burrows as shelter during the day, and lays eggs on a mounded nest which hatch in about three months.
