[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]


I KNEW someone would attempt to continue to argue that elephants can move at
high rates of speed, and Chris & Michael did so. It cannot be overemphasized
that this is simply not true. 

For a multi-tonne animal to move at 20-25 mph it would have to be
galloping!!!! This is predicted by scaling of the trot-gallop transition, and
by the example of rhinos which gallop at these speeds. Have timed them from
videos. The laws of physics and animal biomechanics prevent a giant animal
from walking faster than about 12 mph. The stride frequency would have to be
impossibly high, twice what is attainable.  The very fast elephant in the
race I timed was at its maximum possible stride frequency, so it obviously
WAS going at its fastest speed. No one has ever documented an elephant moving
faster than ~12 mph by a rigorous means. In science that means that higher
speed claims are unverified until proven. 

So those who wish to claim that elephants can move faster need to prove it is
so. Until then I suggest they sit down and work out the stride frequency
required, and see if they can explain out how an elephant can walk as fast as
a rhino gallops in a charge! 

The citation of bee flight as an example of how animal performance can be
underestimated is misleading. Everyone knew bees could fly, it was just that
for a period it was difficult to explain via conventional aerodyanamics. No
one knows that elephants can exceed 15 mph, some people just think so. What
is more appropriate is the excessive speed claimed for the bottle fly in the
1920's. An entomologist standing on a mountain ridge saw one wizz by his
head, and he timed how long it took to cross a meadow. He calculated the
speed at 600 mph and published same in a journal. That's 600, not 60, and it
was not a typo. No joke, I've seen the speed cited in an old Life magazine!
Of course, a fly moving at nearly the speed of sound would have the
characteristics of a pistol bullet - you could never see it and it sure would
hurt awful bad when people were occasionally whacked by fast flies. Other
scientists had a field day panning the poor fellow's mistake. The energy
required to move so fast would be about the same as that involved in firing a
bullet and would incinerate the bug, etc. Of course what happened was that
the fly disappeared from the observer's view long before it reached the edge
of the meadow so he miscalculated the distance traveled by a factor of ten,
and did not think through the insanity of his results. Ya gotta watch out for
those seemingly "fast" moving animals, they'll fool ya! 

As for the energy required to walk and run, for a given animal energy
consumed is the same regardless of speed per unit distance traveled (except
kangaroos). You burn the same number of calories walking a mile as running
it. It is also very energy expensive for an animal to maintain a constant
speed, 4-12 times less efficient than for an animal of the same size to swim
the same distance. Even flying is 3 times cheaper than walking in this
regard. This is why fliers and swimmers can migrate across oceans and
continents, while no land animal tries to do so. Why walking is so costly has
been one of the major problems of biomechanics and bioenergetics.