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Re: ora speeds
Jura makes many errant assertions of the sort that oo commonly afflict the
>>1) Auffenberg's observations agree with those of another study:
Lederer, G. 1942. Der Drachenwaren (_Varanus komodoensis Ouwens). Zool. Gart.
(Leipzig)(n.s.) 14(5/6): 227-244
If I remember HP David Marjanovic correctly, these measurements were taken
from animals at a zoo. Yet, they still represent an independent account of
these animals moving at these speeds. If one doesn't mind translating German
(better if one already knows German), then one might find a data set there.
Incompetent analysis by J. There is no dispute that oras can move at high
speeds. The question is the speed which they can sustain while normally
moving in the wild for hours on end. Zoo data is not relevant. Jura does not
even present a data set showing that zoo oras spend hours cruising at high
speeds, does not even cite any particular speed. Useless as presented by J,
and probably not applicable to wild conditions in any case.
2) Oras, and varanids in general, DO NOT possess low aerobic abilities. They
are highly aerobic lizards (though degree of aerobiosis varies between
species; much as it does in mammals).
Bennet(1972) was one of the first to show this. He compared _Varanus gouldii_
to _Sauromalus hispidus_. He found the monitor to consume twice as much
oxygen as the iguanid, have a much lower lactic acid build up, and recover
from exercise 3 times as fast under high temperatures.
Later work (Hopkins et al, 1995/Frappell et al, 2002) showed that, not only
do monitors show gas exchange abilities on par with mammals, but their
aerobic limitations are exactly the same as the ones found in mammals.
J is completely wrong. There is not a reptile in existence that has high
aerobic capacity. Even the most aerobically capable monitors have a
sustainable aerobic capacity that is patheticlly low, by an order of
magnitude, compared to levels typical in mammals and birds. There is vast
literature on this, I cite abundant refs in DA. J is making the gross mistake
of thinking that since some herps have higher capacity relative to others
that they have high capacity in absolute terms. This is like saying the
Wright Flyer of 1905 had high performance compared to the 1903 original -
which it did - and from that concluding that the 1905 machine had high
performance. Not compared to a Spitfire. Nor is gas exchange capacity
pertinent. It is the aerobic capacity of the entire respiratory, cardian and
muscle system of an animal that matters. No reptile can sustain a high
walking speed on a treadmill or on oepn ground, there have been many studies
showing this. Jura needs to cite the papers showing via direct observation
that reptiles can aerobically or anaerobically sustain walking speeds
significantly over 2 km/h. As it is J appears to have poor knowledge of the
> I timed a large sample of oras from videos and found
> that they move at a typically reptilian pace of 0.5-> 2 km/h.
How, exactly, does one go about doing this?
Again J is unfamilar with the literature. I've published the method and
results in DA and elsewhere. Spend the time and effort to read the published
> When they move at 5 km/h they are hauling, usually > in response to a
stimulus such as a carcasse
> or combat.
While I usually avoid citing nature documentaries when I can, if one watches
the Komodo dragon special of The Crocodile Hunter, one can watch an ora
trotting along at 8 km/hr (according to Steve Irwin). The animal appears very
nonchalant in its movements (none of that muffled machinegun stuff), and
while Steve was winded by the time it stopped, the ora showed no signs of
No this is getting desparate, since citing Steve Irwin as an authority is a
dubious proposition. All the more so since nature documentaries are often
deliberately altered to present a better story, and the story often
represents what the producers think is correct rather than what is really
known. I've seen the sequence and I was not so impressed. No data was
offered. Was the sequence actually a continuous run, or edited to make it
look like one? Was Steve really winded, or was it for dramatic effect by a
celebrity notorius for playing to his audience? How can Jura assess the
recovery status of the ora? In any case the brief sequence leaves completely
unanswered whether oras or any other animal with reptilian energetics can
sustain walking speeds above 2 km/h for hours a day, as per the reptilian
tyrannosaur scavenging scernario. Again Jura fails to comprehend the
irrelevance of his analysis.
>>In a separate post you mentioned that oras achieve their speed by
anaerobiosis. This would be in contrary to data compiled on locomotion for
these animals (no undulations at high speeds), and with data on behaviour
during intense activity (killing and eating its own weight in wild boar in 17
minutes without exhaustion), all of which show them to be aerobic animals.
Furthermore, studies on other monitors (Bennett 1972) show reliance on
anaerobiosis only at very high temperatures. So, where are you getting your
data about them be anaerobic?
Egad! The arrogant incompetence here is breathtaking. Vast pages of research
and literature emphasize that reptiles rely on anaerobiosis in order to
achieve any high level activity (in contrast to insects which have little or
no anaerobic capacity). It's one of the basic features of the group (again
refs are in DA etc). The question is not where do I get my data. It is
whether Jura has more than a superficial misunderstanding of the subject, and
what quantitative data he can cite in support of his thesis which is a
variance with the consensus on reptilian energetics.
J misunderstands the temperature issue, reptiles that cannot achieve high
levels of activity at low temperatures do not need to use anaerobiosis. Only
when warmed up can they be active enough to kick it in. Of course oras live
in a warm place and spend many hours at their prefered body temp. As for the
ora eating boar, can J cite data showing the the lizard really was working
hard enough to be anaerobic, or that it was not anaerobic (which can be used
for many minutes if not at the most extreme levels)? What data gathered at
the time demonstrated it was not exhausted? And again, what is the relevance
of 17 minutes of intense activity to an animal cruising for 12 hours in
search of carcasses?
Before contributing further to these discusssions it would be helpful if J
became thoroughly familiar with and understood the literature, rather than
posting half truths and falsehoods. Most professionals do not participate on
the list because they do not wish to deal with those who have insufficient
Finally, there is no well documented data showing that any reptile can
sustain speeds over 2km/h for hours at a time, and those who wish to assert
otherwise need to cite one or more specific studies (author/s, date,
publication) that establish this beyond any doubt, to the degree that the
ability that of birds and mammals can easily walk at 3 km/h or faster for
many hours is well established. Unless that is done claims of fast walking
reptiles are a nothing more than a mighty wind.