Re: ANIMAL LOCOMOTION (long)

[Jonathon Woolf <jwoolf@erinet.com>]

GSP1954@aol.com wrote:
 
> In this list it has been claimed that elephants can pace, that the amble is a
> version of a pace, and that the pace and the trot are not functionally
> equivalent. None of this is true. In quadrupedal tetrapods, gaits come in
> three basic levels. 

Make it four: walk (and equivalents), trot (and equivalents), canter,
and gallop.

> Walk & amble - These are the slow nonrunning gaits, in which at least one
> foot is always in contact with the ground. The amble is nothing more than a
> faster version of a walk. In mammals, in both the walk and amble legs on one
> side are both in the air for part of the same time. 

However, in the walk there is a significant chance for the two legs on
the same side to interfere with each other, because they do not move in
synch.  In horses this is called "forging."  The faster the animal
walks, the higher the risk of conflict between fore and hind foot.  The
amble does not have this problem, so the amble permits a faster motion
than the walk does.

> Trot & pace - These are the symmetrical medium speed running gaits with a
> suspended phase. They are essentially the same thing, so identical that if
> the animal is seen only in lateral silhouette they are indistinguishable. 

Perhaps to someone not experienced in watching them.  I can tell a
trotting horse from a pacing horse because the pace induces a mild
rolling motion as the support moves from one side to the other.  

> Gallop - This is basically the quadrupedal version of bounding, it is very
> variable in form. In juvenile crocodilians it is a simple bounding run that
> looks like a silly squirrel in armor plate dragging a fat tail behind, in
> bigger mammals it is a complex, asymmetrical affair. If prosauropods galloped
> they may have done so like crocs, ceratopsians more like mammals.

I don't even pretend to understand how you can use the same technical
term to describe the motion of a straddle-legged croc and an
upright-legged dog.  I know little about reptilian modes of locomotion,
but I do know that all mammals gallop basically the same way.  At least,
those that can gallop, gallop the same way.  I doubt a squirrel or a
rabbit has the right build to gallop.  The mammalian gallop as used by
dogs, cats, horses, antelope, etc. is a distinctive high-speed four-beat
gait in which each foot touches the ground separately, always in the
same sequence, with a period of suspension in the middle of the stride
after the second forefoot pushes off but before the first hindfoot comes
down.  "Bounding" is what I could call the unusual movement where
hindlegs are synchronized, as in a cat springing or an antelope pushing
off for a jump.

> Science is like a rough contact sport. Its fun, but you get knocked about,
> and to win you have to know you're business. We all get our bruises and
> sometimes we lose. So play the game with the big boys at your own risk.

So it is, so it is.  And the risk can go both ways.  For example, I just
happen to be acquainted with a gentleman by the name of Jay Haight, who
has fifteen years of experience as a professional elephant-keeper at a
zoo in Oregon, has published sixteen papers on elephants in formal
journals, was designing natural-looking exhibits for elephants before
that was popular in zoos, and is considered one of the foremost experts
in the world on elephants and the keeping of elephants in captivity.  I
queried him on this matter of elephant top speeds.  Here is what he
replied (reproduced with permission):

My question was: 
"I was wondering if you could answer a question for me.  Do you know the
top speed that an elephant can achieve?  Somebody on an Internet mailing
list is claiming they can't move faster than about 12mph, but I keep
running across figures in various books that a charging elephant can
reach 20mph. "

His reply was:

"Parts of elephants can move incredibly fast -- I've seen a quick flick
of a trunk knock a sparrow from flight.  In short distances, the whole
animal itself can be moved very quickly.  Elephants can maintain speeds
of 20 to 25 mph in the course of the first quarter mile or so; the
speeds drop from there.  In the space of twenty feet or so, an elephant
can hit 30 mph.  No "top speed" has ever been published, nor is it
likely to be.  There was a time when a four-minute-mile was considered a
"top speed" for humans, yet that time has been broken repeatedly by
some, and never approached by others (like me!).  The same applies to
elephants.

"According to your Internet friend, humans should be able to keep pace
with an elephant, but in the short haul, they can't.  Humans excel in
paced distance running, so a determined human can eventually overtake a
stampeding elephant.  In a charging situation, distances are typically
very short -- which puts the human at considerable disadvantage. 

"Jay"

-- Jon W.