The Ark Files - Putting Your Foot In It

Imagine trying to balance, walk, run and hunt, kick off attackers or dig a burrow without any feet? Lots of animals have fins, flippers, claws, hooves or paws. They are all feet and have the same basic structure, but they are specialised for different purposes.

Base jumping

Most frogs have webbed feet to help them swim, but the southeast Asian flying frog uses its feet in a very different way ... it has taken to gliding! As the frog leaps it spreads out its long, webbed toes and each foot becomes a tiny parachute. The frog swiftly glides from tree to tree.

Rolling up your sleeves

The platypus has dual-purpose feet. It has webbing for paddling and steering and strong claws for digging tunnels. The platypus can roll back the webbing on its fore feet into its palms and so free the claws for work.

Life in the trees

A good grip is the key to swinging acrobatically through the forest. Primates such as orang-utans and chimpanzees have ideal hands and feet for the purpose, with opposable big toes and thumbs with which to grasp branches.

The gorilla's foot is not so good at grasping and so it spends less time in the trees. When it does come down from a tree it sometimes slides down, using its feet as a brake by pressing the soles flat against the trunk and showering moss, creepers and bark all around.

Avoiding that sinking feeling

Desert dunes are a challenge - the sand is always slipping away under your feet! But this is no problem for camels. Their feet are the size of dinner plates with webbing between the toes. The feet splay out as they walk and keep the camels from sinking into the sand.

Winter olympians

The amazingly agile snow leopard of the Himalayas has cushions of hair on the soles of its paws which give it an excellent grip in the steep and slippery conditions as well as preventing it from disappearing into snow drifts. These hairy pads also protect the leopard's paws from the freezing temperatures and rough stones of their mountain homes.

The feet of polar bears are also thickly covered with dense hairs to stop them from skating over the ice when running. Polar bears' paws are so huge that they can kill a fully grown seal with one sideways blow, smashing its head on the edge of the ice as it pops out of its breathing hole.

The heavyweights

Elephants, rhinos and hippos have large, wide, flat feet with shock absorbing pads. This helps them spread their weight evenly. Their feet are just like tennis shoes.

Too much of a good thing

One of the most fearsome of feet is found on an animal that eats tiny insects. The giant South American anteater has feet equipped with incredibly long, hooked claws which it uses to tear open solid termite hills as though they were made of paper. The anteater is very slow moving, however, for its claws are so long that it has to tuck them inwards and walk on the sides of its feet.

Fatal feet

The large and powerful feet of the monkey-eating eagle of southeast Asia possess long, sharp talons for attacking, killing and dismembering its monkey meal. Goshawks force their dagger-like claws through the skin and body and, by repeated squeezing, into the vital organs of their prey. Falcons use their feet as fists to strike and stun their victims, using their speed to deliver a killing blow.

The tail membrane of most bats extends to the ankles. In the fishing bat, it is attached much higher up at the knee so that the legs are quite free. This means the bat can trail its feet in the water, armed with large toes and hooked-shaped claws. When it strikes a fish, the bat scoops it up into its mouth and kills it with a powerful crunch of its teeth.

Circus lizards

In the tropics there are very clever geckos that can run up walls, scuttle upside down over ceilings, even cling to windows ... and they don't use suction! Instead they have enormous numbers of tiny hairs underneath their toes. These hairs, which are invisible to the naked eye, stick to any minuscule bumps, even those on the surface of glass, providing the gecko with a foothold almost anywhere it likes!

What about the human foot?

We came down from the trees and consequently our feet became more suitable for striding and running. The big toe moved more in line with the rest of our toes and so we lost the ability to grasp tree limbs with our feet. We also developed a slight arch to help us balance in our new upright posture. And unlike the monkeys, we don't waddle when we walk ... well, at least most of us!