If we asked what the fastest animal is on Earth, almost all of us would answer it’s the cheetah, with a top speed of between 95 and 115 km/h. Now the thing, can we say an animal is fast (or slow) because it covers a certain amount of miles per hour? Do these units (miles and hours), invented by homo sapiens, mean anything for other animals? How can we compare the speed of an elephant with the one of a caterpillar?
Perhaps a more appropriate choice for measuring speed could be to determine how many ‘bodies‘ (its own body lengths) per second each animal moves; thus, we’d relate the size to the speed of the animal. This is not very complicated to calculate in the case of elephants, cheetahs or persons; but things get complicated when the ‘little animal’ in question is less than a millimeter.
Recently a group of students from southern California (USA), directed by Professor Jonathan Wright, has achieved to measure, using a high speed camera, how many bodies per second a certain type of mite travels, more concretely the paratarsotomus macropalpis, endemic of the area of southern California. The result is a surprisingly high value, no more and no less than 322 bodies per second, making it the fastest animal (relative to its size) on the face of the Earth.
To get an idea of how fast this mite moves, think that for a human being it would be equivalent to about 2,000 km/h. Note also that, in relation to its size, the fleet cheetah moves at a speed of 16 bodies per second and our admired athlete Usain Bolt just 6 bodies per second. Transported to the world of mite, they’d seem two turtles.
This apparently anecdotal discovery not only sets new speed limits for living organisms, but also reframes questions about the physiology of animal movement and opens the door to new designs in robotics and biomimetics.