Animal Hall of Fame: Smallest

The bumblebee bat tips the scales at about 2 grams and measures between 30 and 40 millimeters as an adult. This tiny animal is found in Thailand and Myanmar.

Sea otters weigh between 35 and 90 pounds. They sleep while floating on their backs on the surface of the water. Sea otters are the only otters that give birth in water. Their ears and nostrils close up when they go underwater.

The hummingbird grows to only 2.5 inches long and weighs only 0.06 ounce. This tiny bird makes its humming sound by quickly beating its wings.

Fairyflies, members of the wasp family, are only about 1/5 of a millimeter long. They are so thin--about the size of a thread--that they can't fly well and rely on the wind to carry them.