Re: ora speeds

[Jura <jura@reptilis.net>]

>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.

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Alright, I'll let that slide as an error in the writing, on my part.

1) Auffenberg states that his observations of 4.8 km/hr search speeds, agree 
with the observations made by the people in the paper cited above. 

2) I am not saying that this represents evidence that oras move speedily, but 
as evidence that they cruise at these 4-5 km/hr speeds.

3) The reference might have come from a zoo, but the observations might have 
come from the wild. I'm going to attempt an ILL of this paper, and see exactly 
which they are.

4) These observations (whether they are based on captives, or otherwise) do 
have applicability to wild animals, as Auffenberg's observations were on wild 
animals.

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>
>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 
>literature. 

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For someone so willing to jump on other people's cases for not citing full 
refs, you don't seem to mind doing the same thing yourself. 

You state that no reptile today is highly aerobic, yet when given evidence to 
the contrary you completely dismiss it. 

The gas exchange ratio IS important to aerobic capacity, as this represents the 
limiting factor in these lizards. It also represents the limiting factor in 
mammals. Bennett's study, Frappell et al, and Hopkins et al's studies all 
looked at all of these factors (not just gas exhange) to determine this. 

As for studies showing treadmill studies of animals moving at higher speeds 
than 1-2 km/hr, I'm not aware of any. Even recent studies, with people who know 
of the aerobic capacities of these reptiles, still keep them trotting along at 
slower paces. 

Why? Not because it is all they can handle, but because the literature states 
that this is a good speed to use for most reptiles. As such, varanids and other 
aerobically capable lizards have to deal with a lowest common denominator 
approach.

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>
>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 
>aerobic distress.
>
>No this is getting desparate, since citing Steve Irwin as an authority is a 
>dubious proposition. 

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I would like to just point out that Steve Irwin does contribute more to 
herpetology than entertainment. He has a scientific background on monitors 
(mostly Aussie), and apparently does contribute scientific info on the breeding 
of certain species. Admittedly nothing too helpful for this discussion, but he 
is more qualified than most people give him credit for.

=========================================


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. 

============================================

All that coming from a guy who cited a National Geographic PICTURE as evidence 
of crocodylian "anaerobic inferiority." I don't see how you were able to assess 
the exhaustion of that croc, from said picture, yet you didn't mind citing it 
in your Terramegathermy paper. Well I've seen it, and was not so impressed 
either. 

Anyway, like I said, I usually shy from nature docs as citation when I can. If 
there was more film available for oras, I would probably have used a better 
example.

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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). 

===============================================

Ignoring the ad hominems, I specifically asked where you got your info on 
anaerobiosis being used by komodo dragons, during activity. It would appear 
that you are assuming that just because anaerobic movement is common in most 
reptiles that have been studied, that this is found in every species. This is, 
essentially, the exact same thing you were chastising me for above.

So, again, I ask you: where are you getting your info that Komodo dragons use 
anaerobiosis to move at, say, 5 km/hr?

===============================================

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. 

=================================================

I already gave you 4. Auffenberg you already know (and seem to all too readily 
discount), the full citations for the other 3 studies are:

Bennett, A.F. 1972. "The Effect of Activity on Oxygen Consumption, Oxygen Debt, 
and Heart Rate in the Lizards _Varanus gouldii_ and _Sauromalus hispidus_".
Journal of Comparative Physiology. 79, 259-280.

Frappell, P. Shultz, T. & Christian, K. 2002. "Oxygen transfer during aerobic 
exercise in a varanid lizard _Varanus mertensi_ is limited by the circulation". 
The Journal of Experimental Biology 205, 2725?2736

Hopkins, S.R. Hicks, J.W. Cooper, T.K. Powell, F.L. 1995. "Ventilation and 
Pulmonary Gas Exchange During Exercise in the Savannah Monitor Lizard (_Varanus 
exanthematicus_)". The Journal of Experimental Biology 198, 1783?1789 

The last two are available online at the JEB website. Just search for the 
keywords at:

http://jeb.biologists.org/search.dtl

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>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. 

========================================

I'm not exactly sure of what you are talking about here. Where did I mention 
aerobic activity at low temperatures?

==========================================


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? 

==================================================

The data came from:

Auffenberg, W. 1972 "Komodo Dragons". Natural History. 81(4): 52-59

It shouldn't be too hard to find. Whether or not it required anaerobiosis might 
be a matter of opinion. In Auffenberg's 1981 study, he shows ingestion rates of 
between 1-2.5 kg/min for large oras. Comparative data with tigers showed their 
consumption rate was about 3 kg/min and 0.1 kg/min for ora sized leopards. 

Ignoring the fact that killing prey items (especially prey of similar size) is 
not easy, consuming the animal at that rate is probably not that energetically 
cheap. Even crocs (which do hunt using anaerobiosis) take brief rests after 
killing large prey.

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And again, what is the relevance 
>of 17 minutes of intense activity to an animal cruising for 12 hours in 
>search of carcasses? 

=================================================

Because 17 minutes of intense activity is going to consume more energy than 12 
hours of moderate to low activity.

==============================================

>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 
>knowledge bases. 

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In my experience, the reason most professionals don't participate on the list 
is because of the frequency that new and controversial ideas (e.g. _T.rex_ 
running abilities, or lack thereof) tend to get thoroughly flamed by those who 
either immediately write it off as wrong regardless of the data presented, or 
who haven't even read the paper. Also, know-it-all attitudes aren't too helpful 
either.

Jura

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"I am impressed by the fact that we know less about many modern [reptile] types 
than we do of many fossil groups." 
- Alfred S. Romer  Osteology of the Reptiles

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