Perhaps, one of the most exciting sights in nature is to watch a tiger go into attack mode. First, crouching down and step-by-step stalking its chosen victim, before charging out and springing at it. Tigers, for one, are well equipped to do that. Apart from their camouflage, their padded paws make not a sound over crackly ground as their fearsome 10 cm-long, razor-sharp claws are retracted with the help of ligaments requiring no effort from its muscles and then slipped out like flick-knives when the tiger attacks its victim (or has to defend itself). This retractability enables the claws to remain sharp no matter what terrain the tiger traverses. The tiger’s hind legs are longer than its front legs enabling it to leap up to 10 metres and the front legs have dense, closely knitted and strong bones to support the effort needed to fell, large game and to absorb the impact of landing or running. Dewclaws located further back on the foot help to grip the prey. While the curved claws may assist the tiger to climb trees – they, along with the weight and bulk of the animal – make a headlong descent an undignified and awkward process. We have been so impressed by the lacerating power of tigers’ claws that we have made weapons out of metal resembling them: the notorious ‘wagh nakh’ that famously Shivaji is said to have used to disembowel the Bijapur Sultanate General Afzal Khan. Bears have massive powerful hindquarters which give them a clumsy bounding gait (but they can run faster than any human) and are armed with a series of deadly, comb-like claws – used more to dig up roots and tubers and small animals and, if attacked, to rip their attacker to shreds. The grizzly’s pale-coloured claws can be over 10 cm long so you can imagine the damage they can do when the animal takes a swipe at you. Evolutionary engineering has really taken off (if you will excuse the pun) in birds. The primary mode of locomotion for most birds is flight – so their legs and feet have evolved over time to do other jobs. Unlike us, birds walk on their toes and not on the flat portion of their feet. The bird’s knee joint points forwards but is usually not seen, tucked behind feathers, but it's ankle points backwards and is clearly visible. Of course, flightless birds like the ostrich and rhea, use their enormously long and dangerous legs and feet to run – the ostrich at 70 kmph – and as weapons of defense: the ostrich, in spite of its delightfully pansy way of running, can shatter a lion’s jaw with a well-aimed kick. The dangerous, ill-tempered rhea, too, can rip you to shreds. Most perching birds have four toes tipped with claws on their feet – three forward facing and one rearward. Woodpeckers, however, have two rearward facing toes (and claws) to enable them scuttle up and down vertical surfaces of tree trunks in their hunt for insects as do raptors to enable them to grip their prey. Most birds hop and saunter while on the ground, and for many of them their feet are used to give them the momentum for take-off. They will crouch just a bit and then spring into their air as their wings unfurl. And, of course, their legs are also used as landing gear – some large species like swans and pelicans not only use their webbed feet to provide the momentum for takeoff from water but also as brakes upon landing. The albatross, with its enormous wingspan sprints down special ‘runways’, against the wind (just as airplanes do) to gather enough momentum for a take-off, which they otherwise could not manage. Birds, like swifts and swallows, which love life up in the heavens and are loath to touch down have small tucked up legs and feet, good only for clinging to cliff edges and overhangs where they nest. Parrots and parakeets, being the intelligent souls they are, use their feet and claws like hands – holding up fruit or nuts to their beaks while eating. Bee-eaters, kingfishers and burrowing owls use their feet as spades as they excavate tunnels for nesting in sandy cliff faces or in the ground. The feet of ducks, geese and swans have evolved into webbed paddles – which help them motor and steer their way across the water, most brightly coloured. They give these birds their hilarious waddle when on land. Wading birds like herons and storks have long legs which help them stalk in ponds and lakes as they fish. Other waterbirds like the jacanas have huge spider feet, which spread their weight over the floating leaves on which these birds skulk looking for frogs and other aquatic life, carefully, step by step. You might wonder why birds don’t fall off their spindly perches while sleeping. Such birds, known as passerines, have a special tendon locking arrangement in their feet; a tendon at the rear of their legs is automatically tightened and pulled when the leg bends making the foot curl tightly around the branch or twig when a bird lands, and is locked in place by another tendon. Birds also use their feet during courtship, while hunting (the claws of the Harpy eagle are as deadly as a grizzly’s), and to maintain body temperature by heat exchange: they can both warm and cool the bird. That’s why you often see birds like flamingoes and storks standing pensively on one leg, the other tucked into their plumage. Others like some vultures may defecate on their feet to enable evaporative cooling. Now that really is disgusting!
