Brazilian pygmy marmosets are the smallest monkeys in the world, measuring at 14-16 cm long and weighing a mere 119 g. They are found in Peru, Ecuador, Colombia, Bolivia, and Brazil. Pygmy marmosets occupy mature evergreen forests in and at the edges of periodically inundated river floodplains. Adult pygmy marmosets have tails that are longer than their bodies and marked with conspicuous black rings.
Pygmy marmosets can leap up to five meters. They are also able to turn their heads 180 degrees, which allows them to scan the environment for predators while vertically clinging to a tree. A group of pygmy marmoset ranges in size from two to nine individuals – they live together on a single tree. Because of their extremely small body size, pygmy marmosets are subject to predatation.
2. Cuba's Bee Hummingbird
The bee hummingbird weights about 1.6 grams and is approximately 5 cm in length, making it almost the size of a bee and thus the smallest bird in the world. The bee hummingbird also lays the smallest eggs in the word – that is about the size of your smallest fingernail. Besides their size and small eggs, they also have the smallest number of feathers – about 1,000 feathers – other bird species have up to 25,000 feathers. However, they have the second fastest heart rate of all animals, to sustain their high metabolism.
They also have the highest body temperature of all birds, but it drops during the night to save energy (as the bird would lose too much heat because of its small size). The hummingbird flies with 80 wing beats per second, a rhythm at which the human retina cannot detect. During the courtship displays, the male flaps his wings up to 200 times per second. Bee hummingbirds eat half their total body mass and drink 8 times their total body mass each day.
3. Ducky the Short-coat, Male Chihuahua
The smallest living dog, in terms of height, is a short-coat, male Chihuahua called Ducky. Ducky is 12.38 cm tall and is owned by Lisa Messier of Charlton, Massachusetts, United States.
4. Mr. Peebles
The Guinness Book of World Records has verified that the world's smallest living cat is Mr. Peebles. He is approximately 15 cm long and fits perfectly in a 200 ml glass. Mr. Peebles lives in central Illinois, is two years old and weighs about three pounds.
5. India's Venchur Cow
India's Venchur cow is a rare breed of cattle named after the village of Venchur in India's Kerala district. With an average length of 124 cm the Venchur cow is the smallest cattle breed in the world. The cows are valued for the large amount of milk they produce in relation to the small amount of food the need.
Standing approximately half a meter, she is never going to be a champion show-jumper. In fact, the tiny mare is so small she would struggle to leap over a bucket. But such things are of little concern for feisty Thumbelina who has just been officially recognized as the world's smallest horse.
The five-year-old received the title from the Guinness Book of Records after her astonished owners realized she was never going to grow any bigger. She was born on a farm in America to a couple who specialize in breeding miniature horses. These popular show horses usually weigh about 250 lb. and reach a height of 34 inches when they are fully grown.
7. The Paedocypris Carp, Sumatra
The Paedocypris carp is the smallest fish, found in the peat swamps in Sumatra. Adults grow only to about 8 mm. This unusual species has a rudimentary skull which leaves the brain exposed. It feeds primariliy on plankton.
8. The Pygmy Jerboa, Asia (Cardiocranius paradoxus)
The pygmy jerboa is the world's smallest rodent. At about 47 mm, the pygmy jerboa is one of the smallest mammals in the world. While there are a few different species spread out across Central Asia and China, it is best loved in Kazakhstan, where it is featured on postal stamps.
9. The Blind Threadsnake (Leptotyphlops Carlae)
TheBlind Threadsnake is the world's smallest specie of snake, with adults averaging approximately 10 cm in lenght. Found on the Carribean islands of Barbedos, the specie – which are as thin as a spagetti noodle and small enough to fit comfortable on a U.S quarter – was discoverd by Blair Hedges.
9. Brazilian Psyllophryne Didactyla
The smallest frog in the world is the Brazilian Psyllophryne Didactyla or Gold Frog. It can be found in the Southern Hemisphere mainly in Brazil. The Gold Frog is only 9.8 mm long.
10. The Dwarf Gecko (Sphaerodactylus ariasae)
The world's smallest lizard has been discovered on a tiny Caribbean island off the coast of the Dominican Republic. The newly-discovered species not only ranks as the smallest lizard, but it also as the smallest of all 23,000 species of reptiles, birds and mammals. Sphaerodactylus ariasae is only about 16 millimeters long, or about three quarters of an inch, from the tip of the snout to the base of the tail.