Land mammal: The bumblebee bat tips the scales at about 2 grams and measures between 30 and 40 millimeters as an adult.

Marine mammal: Sea otters weigh between 35 and 90 pounds.

Bird: The hummingbird, which grows to only 2.5 inches long and weighs only 0.06 ounce.

Fish: The Paedocypris progenetica, which was recently discovered in Indonesia, measures just over 1/3 of an inch long.

Reptile: The British Virgin Islands gecko is about ¾ of an inch long when full grown.

Insect: Fairyflies are only about 1/5 of a millimeter long.

BiggestAnimal Hall of FameFastest