

CHIHUAHUAS: Chihuahuas are among the smallest dogs. Here, a miniature Chihuahau and Jack Rusell terrier cross, Tom Thumb, sits in a teacup. Tom Thumb measures less than four inches from the tip of his nose to his tail and only weighs three ounces. He was born in late July 2009 and is a contender for the title of World's Smallest Dog. Based on the size of Tom's paws and body proportions, his owner does not expect the dog to grow more than an inch or two more. Newscom/FILE
MINIATURE HORSES: Thumbelina, currently the world's smallest horse, now stands at just 17 inches tall and weighed just 9 pounds at birth. Her extraordinary size has been linked to dwarfism, making her a miniature of a miniature. Because Thumbelina's legs are proportionally smaller than her body and head, she has to wear orthopedic fittings to straighten out her small skeleton. Thumbelina is seen here in October 2006. WENN.com/Newscom/FILE
CHAMELEONS: An employee displays the world's smallest Pygmy Leaf Chameleon at Tokyo's Sunshine International Aquarium in January 2002. The chameleon is a rare species from Madagascar measuring only one inch in length and weighing only three grams. Yoshikazu Tsuno/AFP/Getty Images/Newscom/FILE
SEAHORSES: A pygmy seahorse is seen in the Lembeh Straits off Indonesia. The tiny seahorses are typically just 16 millimeters long, smaller than most fingernails, and some were found to be as small as 13 millimeters long. Newscom
HUMMINGBIRDS: Bee Hummingbirds are the smallest birds in the world. This one is seen in the Zapata swamp in Cuba. The birds are typically 2 inches in length and weigh only 1.8 grams. Newscom
SNAKES: The world's smallest snake, Leptotyphlops carlae, measures just under four inches in length at adulthood. The species is found in Barbados and is as thin as a spaghetti noodle. WENN.com/Newcom
FISH: The Stout Infantfish is seen here, found by Australian scientists, weighing just one milligram and growing to only seven millimeters in length. The fish only lives for two months, does not grow fins, teeth, or scales, and has the world's smallest vertebrate. Carl Bento/AFP/Getty Images/Newscom/FILE
COWS: A three day old Indian Zebu calf gets its first taste of milk from a bottle. At three-feet tall and about 300 pounds, these gentle, hardy cattle common to India and Asia are gaining popularity as low-maintenance novelty pets for rural homeowners in the United States. The world's smallest cattle (not shown) is a rare breed of the Indian Zebu called the Vechur cow. Newscom
EINSTEIN: Garret Mullen watches a baby pinto stallion, Einstein, in Barnstead, NH, on April 25. The tiny horse, born on April 23, could challenge Thumbelina for the World's Smallest Horse. Einstein was born at just six pounds and 14 inches, Thumbelina was nine pounds at birth. Einstein is also not a dwarf horse, his head, body, and legs are in proportion of that of a normal miniature horse. Jim Cole/AP