Recent Komodo postings of Dr. Bryan Fry

[Zoo Nanny]

Originally Posted by murrindindi

Thanks for that link, though I`m sure the "doubters" will find something/many things/everything?) to dismiss!

I can't take credit GatorHunter1231 originally posted it.

[murrindindi]

Originally Posted by formica

its relative isnt it, just because it works best for the Komodo, doesnt make it more (edit: advanced) than all other reptiles, which is what was stated earlier in the thread

No, that was my mistake is using the word "advanced" rather than complex, it doesn't take away from the fact they clearly are more adept at killing their prey because they have a very efficient venom and venom delivery system. If it weren`t efficient (of benefit) they surely would have lost that ability by now?
You are commenting on animals that you are not yet that familiar with at this point in time. I truly hope your interest with Varanids will continue and before long you`ll have deeper understanding (I`m not being patronising).
I must say it`s nice to have a civil discussion, thanks for your input (and everyone else`s), whether we agree entirely or not!

[murrindindi]

Originally Posted by Zoo Nanny

I can't take credit GatorHunter1231 originally posted it.

Take the credit, it won`t come around too often....

[Zoo Nanny]

murrindindi I have to agree with you this discussion has been really good. I've always found documentaries on Komodo's to be fascinating. I've learned a great deal more today from this discussion and posted links than from any documentary I've seen. So thank you folks for peaking my curiosity even more and supplying the information to learn from.

[infernalis]

Originally Posted by murrindindi

Shhhhh, we don`t want Bryan to know there are people who disagree with his findings.....

I like his response to the naysayers, but I would break forum rules posting it.

[infernalis]

The Myth of the Komodo Dragon?s Dirty Mouth – Phenomena: Not Exactly Rocket Science

[venomdoc]

Some sensible questions here. First, I would like to stress that at every opportunity we have gone to great pains to stress that anguimorph lizards are of but of trivial direct medical importance to humans (with the exception of helodermatids and of course the komodo dragon).

The anguimorphs have a combined arsenal system employing teeth and venom. Helodermatids are one extreme, with the deeply grooved gracile teeth restricted to a venom delivering role. In contrast, komodos have the large serrated teeth as the primary weapon, using a grip-and-rip strategy to inflict deep parallel wounds. Mechanical damage that in some cases results in very rapid death from blood loss (eg slicing the femoral artery). The role of the venom is to exaggerate the blood loss and shock inducing mechanical damage caused by the bite. We have identified two main actions common to all anguimorph venoms: anticoagulation and hypotension. Enough loss of blood would lead to a drop in blood pressure sufficient to induce shock or unconsciousness. So anticoagulant toxins facilitate a steady march in this direction. Similarly,hypotensive toxins accelerate the unconscious endpoint.

Komodos evolved not in Indonesia but in Australia, and were not the biggest to have roamed, at least two larger varanids existed to predate on megafauna. The second largest radiated to Timor while komodo radiated to Flores and nearby islands. The modern day situation is that the komodos have three mammalian potential prey choices. All of which are feral. The introduced pigs and deer are within the natural prey size (40-50 kg) while the buffalo are dramatically larger than would have been a reasonable size for komodos to kill and also occupy an ecology unlike anything in Australia.

These collective differences are starkly reflected in attack success. Attacks on pigs and deer are extremely successful. About three quarters bleed out within the first thirty minutes and another approximately fifteen percent succumb within three or four hours. Repeated attacks by the same or other komodos is not uncommon. In dramatic contrast is the outcome of attacks on water buffalo. Which invariably get away, with deep wounds to the legs. Upon which they go and stand in feces filled watering holes. Creating a perfect scenario for dramatic infections. Not from the dragons mouth, but rather having an environmental source. Deep wounds in feces laden water is a perfect scenario for the flourishing of bacteria, particularly the nasty anaerobic types. Thus, the sampling of komodo mouths that purported to show them harbouring pathogenic bacteria neglected to sample the real source of any infection to the water buffalo: the faeces filled waiting hole the dragons recently drank from. It has been a man made artificial scenario all along that has nothing to do with the evolution of the predatory ecology of komodos.

Having gotten septicaemia in Flores from deep lacerations resulting from a boating mishap in Flores harbour (water that is pretty disgusting) I can attest to how quickly such environmental sources can produce life threatening infections. As a consequence of the Flores doctor doing a shockingly inept job of cleaning up the wounds before stitching them up, I ended up delerious and near unconscious in the Bali International SOS clinic 36 hours getting emergency IV antibiotics.

There is nothing special about komodos. They are simply the largest extant species of a clade that had two extinct larger species and has two extant species (V. varius and V. salvadorii), all of which share the unique large,blade like serrated teeth. None of which have ever had the slightest whiff of using bacteria as a weapon.

As for the relative complexity of the varanid venoms glands, this was from our 2009 paper when we discovered it had six discrete compartments. More than any other reptile. However, when in 2010 we looked at a variety of anguimorpha lizards, varanid and non-varanid, we discovered that the ancestral condition was to have one gland per tooth, so 15 or more small glands for anguiids for example, with these glands fusing into larger structures independently in lanthanotids/varanids and also in the helodermatids. So the lanthanotid/varanid gland structure comprised of a encapsulated gland with fused compartments (6 total including one massive one as per the images on my webpage www.venomdoc.com) is equally derived to the helodermatid. However, the most advanced venom delivery architecture in the reptiles is of course the three independent lineages of front fanged snakes (Atractaspis, plus elapids and vipers), with the vipers the most intricate due to the hinged fangs.

Cheers
Bryan

[infernalis]

Thank you for taking the time to post Bryan.

[formica]

fascinating read, yes thanks for taking to the time to post and answer the questions, much appreciated!

I am surprised that anticoagulant and hypertensive toxins are not of great value to medical science, considering the accelerating rise of heart disease and other related conditions - is there anything that makes the Komodos particular toxins unsuitable for study, or perhaps they are already known from other species?

good to hear you recovered from septicemia! Had that myself years ago, not from anything half as interesting as an expedition to Indonesia tho lol

thanks again for posting Brian!

[Rob_H]

Attacks on pigs and deer are extremely successful. About three quarters bleed out within the first thirty minutes and another approximately fifteen percent succumb within three or four hours. Repeated attacks by the same or other komodos is not uncommon. In dramatic contrast is the outcome of attacks on water buffalo. Which invariably get away, with deep wounds to the legs.

Bryan, there's no doubt you've shown the proximate components very well (let's be honest, that's a big understatement), but these sentences here, the ecological and adaptive components, are something that obviously hinges your entire argument together. I assume these statements about hunting efficiency are based on data you're writing up (or have you published this already?), in which case I'll hunker down with trepid anticipation .

There have been many examples in behavioural ecology where perceived importance from lab-based work simply fail to extrapolate to ecological reality, which is why many on the adaptive side of the fence tend to hold their breath before getting too excited with these kinds of studies. I hope you'll forgive why there are a few 'naysayers' for now until you show convincing foraging/field data.

It has been a man made artificial scenario all along that has nothing to do with the evolution of the predatory ecology of komodos

I see where you're coming from of course, but there are many examples of foraging that rely heavily on human introductions. A classic is tool-use in New Caledonian crows... one of the most sophisticated animal behaviours known, and yet the major current adaptive importance on tool use seems to be for extracting a beetle larva from a human introduced tree species.

Important in evolution? Who knows, but it's likely... these birds get around half their fat and protein from these larva. Important for current survival? Absolutely. Many people find both those questions equally interesting, so if Komodo's are getting a significant proportion of their diet from introduced buffalo that are carking it due to bacterial infections following a lacerating and venomous bite, then I guess who cares (except the mechanistic guys ) where the sepsis comes from.... a really cool functional question is whether the Komodo's have adapted their foraging ecology to accommodate this new food source. But if you're wanting to rule out Auffenberg et al's septic bite idea, then I just can't see how you'll do it convincingly without observational data showing bitten buffalo survive/don't get sepsis when they don't wallow.... Unless you get welfare approval for an experiment of course (little chance of that in the UK!).

And just for the record (this isn't directed at Bryan), there's nothing wrong with being a 'naysayer'. I'm sure venom is extremely important for these guys in the context specified (medium-sized mammal predation). However, disproving other people (i.e. the septic-bite brigade) obviously requires much more effort to be convincing, and it's something you need to live with when you're publishing controversial ideas in science. I personally think there's just one more (admittedly quite big) piece to the puzzle before everyone else comes crawling to the pedestal...

Cheers,
Rob

[MDT]

Great post Brian.....the components inducing hypotension and anticoagulation...has your team identified what they are? Do they correlate with any other venoms you have studied?

I ask because one of the most "complicated" envenomations I've treated (essentially all North American pit vipers, except this one) was a Gila bite. The patient developed significant hypotension requiring aggressive use of pressors and mechanical ventilation. He ultimately did well, but it was sketchy for several hours. Your statement made me wonder if there were any similar components...

[venomdoc]

Rob H, those numbers regarding relative predation/escape rate of buffalo vs pigs/deer are based not only on my own field observations from four expeditions to Rinca and Komodo but also congruent results from a larger sample size published by Tim Jessop from more trips to the same locales. So the numbers are solid. In this case, it is actually the field observations that stimulated the lab work, not the other way around.

[venomdoc]

MDT, yes we have published the toxins workup for komodos as well as other varanids as well as other anguimorpha lizards. The articles can be downloaded from my webpage www.venomdoc.com. However, this one hasn't been added to the page yet
http://www.venomdoc.com/downloads/20...af_cutters.pdf
All are linked there except the bacteria study which I haven't had a chance to update on the page yet. Here it is http://www.venomdoc.com/downloads/20...o_bacteria.pdf

[MDT]

Cool...I'll check them out. Thanks so much!

[smy_749]

Originally Posted by venomdoc

MDT, yes we have published the toxins workup for komodos as well as other varanids as well as other anguimorpha lizards. The articles can be downloaded from my webpage www.venomdoc.com. However, this one hasn't been added to the page yet
http://www.venomdoc.com/downloads/20...af_cutters.pdf
All are linked there except the bacteria study which I haven't had a chance to update on the page yet. Here it is http://www.venomdoc.com/downloads/20...o_bacteria.pdf

Didn't have a chance to read through yet, but I noticed the list of bacteria. I had no idea there were so many present. Just about everything I studied in college and then some. And I'm a micro bio major.