The smallest animal on earth is the tardigrade. The tardigrade is also known as the moss piglet or water bear. More »

Leaving aside invertebrates, which are often microscopic, the smallest land vertebrate is Paedophryne amauensis. This tiny frog was discovered in the jungles of New Guinea, and adults are only 0.27 inch long. More »

The largest animal is the blue whale, Balaenoptera musculus, which grows to a maximum of 110 feet long. The smallest animal is the crustacean Stygotantulus stocki, which grows to 94 micrometers, or less than 0.004 inches... More »

The tardigrade (Hypsibius dujardini), also known as the water bear, is considered the toughest animal in the world. These micro-animals can survive in environments that would kill almost any other creature. More »

The strongest animal on Earth is the blue whale. The blue whale is also the largest creature in the entire world. More »

The animal that has the fewest neurons and is therefore a candidate for being the least intelligent is Caenorhabditis elegans, a nematode worm that lives in the soil. This nematode is the first animal to have its nervous... More »

The slowest living creature on Earth is the sloth, which is an herbivorous mammal that is primarily found in South and Central American rain forests. Sloths are especially slow on land because they have weak hind legs th... More »