Walking, crawling, hopping, slithering, creeping, gliding, leaping–the ways animals (and people) get from place to place are endlessly diverse.
This ability to move is one of the main differences between most animals and most plants, and has a definite survival value, because when the glaciers start pushing south or food or water fails, species that can migrate in search of warmer weather or greener pastures have the edge over those that can’t.
For an individual, locomotion has an even more immediate survival value: it allows it to run away. When a beaver munches on a nice succulent willow, the willow pretty well has to put up with it. But when that same beaver is attacked by a cougar, the beaver can save its life by diving back into the river and swimming out of reach.
Of course, running away is of particular importance if you’re on the wrong end of the food chain. For those at the top–predators like the frustrated cougar above–locomotion is great because there are lots of other yummy things out there besides lucky beavers to be chased and caught. A wide-ranging predator has obvious advantages over one that has to sit and wait for prey to come to it (like the Venus flytrap).
However, as economist Adam Smith said (if not in these exact words), “there ain’t no such thing as a free lunch.” Animals pay a price for all this running around. For one thing, they require a lot more energy than plants, which means they have to take in more nutrients. Secondly, their bodies undergo a lot more wear and tear than does the average lichen. This may be one reason why plants, not animals, hold the record for longevity. The longest-lived animals (turtle, parrots and people) may live to 100 or more, while the oldest plants (the bristlecone pines of California) are already at least 4,600 years old.
However, locomotion is so widespread that animals obviously find it worth the cost. And as I said at the beginning, the means employed are incredibly diverse.
Even the number of limbs used in locomotion varies from animal to animal. At the bottom end of the scale, with no limbs, are snakes. Next come snails, with only one limb. They don’t exactly burn rubber when starting out on a patrol of the pond, but ostriches have only one more locomotive limb and they can exceed 80 kilometres an hour.
Dolphins actually have three limbs; two fins in front and a single paddle on the tail. Rabbits, cats, dogs and thousands of other animals have the “normal” four limbs; but you’d have to say that the New World monkeys, which use their tails to help maneuver around in the branches, have five.
Insects, of course, have six limbs; but the tiny springtail also uses its hinged tail as a catapult to launch itself into the air, giving it seven. Everybody’s favorite creepy-crawlies, the spiders, have eight, while certain starfish have nine. (Other starfish have anywhere between five and 50.) Lobsters have 10 limbs, eight walking legs and two for catching prey, but bragging rights in the category of Most Limbs Used Without Them Getting Tangled belong to the millipedes, who have as many as 710.
These limbs are used in many different ways. Ducks waddle, snakes slither, crabs scuttle, horses gallop, cows generally plod. But they have one thing in common: when they have to run away, faster is better.
Of course, fast is relative. The fastest turtle in the world has never broken the 16-kilometres-an-hour barrier. A mouse might. Bats and roadrunners (“Beep! Beep!”) fly and run, respectively, at up to 32 kilometres an hour, a cat can reach 48, and owls and rabbits have been clocked at up to 54. At the top of the list for ground animals is the cheetah, which burns up the veldt at close to 100 kph.
Some animals don’t run fast but have developed an alternate strategy: JUMP!
Humans don’t do too badly in this regard. The human record for the standing broad jump, set in 1968 by Arne Tverrvaag, is 3.71 metres, well up on your average cottontail or Goliath frog, which both manage just under three metres. However, large dogs can jump 5.25 metres (double that in a running leap) and kangaroo jumps have been documented at up to 14.7 metres. (Flying fish can leap out of the water and cover as much as 70 metres, but they cheat by gliding.)
Absolute measurements aren’t the only way to look at leaping prowess, either. A flea can only jump about 33 centimetres–but that’s the equivalent to a human jumping over an eight-story building and landing almost a kilometre away. Or consider the grasshopper, whose legs develop a thrust of more than 20,000 times its body weight. Think of the rebounds a 100-kilogram professional basketball player could make if his legs could develop two million kilograms of thrust! (More accurately, think of the hole he’d make in the ceiling on his way into orbit.)
But while humans may not be the stars of the animal world in pure physical abilities, when it comes to locomotion, we’ve beaten every other species through technology. Airplanes, boats, submarines and the ubiquitous automobile have given us abilities we don’t physically possess, like flight, and speed and power undreamt of even by the grasshopper and the cheetah.
You might say we’ve become the lords of locomotion.