Feet, paws and claws: Masterpieces of evolutionary design

The axolotl, also known as the Mexican walking fish, is an amphibian considered one of the world's most unusual and unique species of salamanders. Axolotls don't undergo metamorphosis when they reach adulthood, like most insects or amphibians (caterpillars and tadpoles, for example). They have a unique ability to regenerate their organs and lost limbs — including, of course, their feet.

The foot of the giant Northern Luzon cloud rat next to the foot of a pygmy cloud rat. Both animals live in Southeast Asia, in the Philippines. Technically, they aren't actually rats but rather tree-dwelling herbivores. Their habitat and behavior is like that of a squirrel. And their feet are very well suited for climbing trees, and scuttling away quickly from predators.

Geckos are a type of lizard that are found on almost every continent in the world. They love to eat insects and spiders for lunch. And they can move just like Spiderman with their sticky feet. Geckos have microscopic hairs, called setae, on their toes. The hairs are only few nanometers in diameter and enable the reptiles to climb up even the slickest of surfaces.

When this "Jesus Christ lizard" is fleeing from predators it gathers speed and runs on its two back feet. Common basilisks have large hind feet with scaly fringes on the sides of the third, fourth and fifth toes. When jumping into the water, pockets of air form between the toes. With each step the pockets are newly filled. Smaller basilisks can run on water for up to 20 meters.

Water striders don't need to run to stay above the water, like the basilisk does. The surface tension keeps them afloat. The bottoms of their feet are covered with thousands of microscopic hairs — similar to the gecko. Tiny grooves between the hairs make the legs water-resistant. The water strider likes to hunt smaller insects on the water's surface.

Goats are funny creatures, just as much at home on rocky mountains and ice as they are climbing trees. Their unique hooves give them incredible grip and traction on even the most slippery, rocky terrain. Mountain goats can jump over gaps several meters long. They use their unique climbing skills to evade predators, such as bears, mountain lions or wolves.

Bats can see in the dark using a special sonar system called "echolocation." When they aren't flying, they spend the day hanging upside down in dark spaces. Their feet are designed as the perfect climbing tools, clinging to rocky and woody surfaces. When upside down, the pure weight of the animals holds their claws in a closed position — they don't need muscles to keep their claws tightly gripped.

Orangutans are known for their long, curved fingers and toes. Having four "hands" is certainly better than just two. Their feet and hands are very similarly structured and perfectly designed for climbing up trees, gripping and swinging. Orangutans live in the rainforest, mostly above ground where they are protected from ground dwelling predators.

Horses usually weigh between 400 and 900 kilograms (880 to 2000 pounds). The hoof helps absorb 70 to 80 percent of the impact of the horse's weight and speed, which can get up to 88 kilometers per hour. The hoof's hard outer shell offers excellent protection for the softer, more sensitive inner hoof, which helps pump blood into the leg and maintains circulation.

Their name in Latin means "one hundred legs." But despite their name, centipedes can have varying numbers of legs, ranging from 30 to 354. Centipedes are members of an invertebrate class called Arthropods. They can be found on almost every continent except Antarctica. Their numerous feet help them orientate themselves in dark areas (like antennas), so they can avoid getting stuck in tight spaces.

Penguins don't get cold feet. Like other birds, they have a fine grid of blood vessels that act as a countercurrent heat-exchanger to keep their feet warm. Their little webbed feet transform into fins when swimming, stiff as a board and powered by their strong muscles. Combined with the perfect torpedo-like shape of the penguin, they propel it underwater to between 10 and 20 kilometers per hour.