tegu eats a rattler

tegulevi · Respected Member Joined: Mar 10, 2005 Posts: 489

I got a set of lizard books from my library and there was a coll pic in there of a (mislabeled) blue tegu eating a rattlesnake. it just got me wondering id over the years they have developed an imunity to rattler venom, like some monitors are believed to have to cobra venom.

what s everyones opinion on this

tupinambis · Posted: Wed Oct 12, 2005 11:10 am Post subject:

I don't think there's any research done on this, but I doubt it is likely. Snakes don't make up a large portion of their diet in order to have exerted enough selective pressure to have evolved this trait. However, there is the distinct advantage of their rather tough hide that they do have; chances are the snake either didn't get through the integument or the snake was found already deceased.

alex · Valued Member Joined: Aug 03, 2005 Posts: 106

I also really doubt it - look at the number of animals that quite competently kill and eat rattlesnakes that aren't immune to their venom, vs the one snake genus that seems to be able to handle the venom. Factor in the number of species who eat carrion rattlers, and it's really unlikely tegus are attacking, killing and getting bitten repeatedly with biological mechanisms to compensate for envenomation from a photo in a book. While it's a useful trait to have, all biochemical pathways have a cost to them that must be outweighed by the benefit, and casual dining on rattlesnakes is unlikely to provide enough of a boost to justify the maintenance of that trait.

Slizarus · Posted: Wed Oct 12, 2005 7:19 pm Post subject:

And besides, what no one else brought up is this: How many Crotalids really occur in South America?
Oh sure there are plenty of vipers.. but rattlers?

There just wouldn't be any real chance for as a species, let alone a genus to develop any immunity to it.

I've heard quite a bit about their thick skin, and while Crotalidae have extremely impressive fang structures from mobility to just the venom delivery.. far improved over an Elapid's.
I don't even think they'd have any chance to put in a good strong strike with enough force to penetrate it, deep enough to get into the blood stream if anything.

So... I think we're just dealing with thick skinned, hard headed lizards who love us... let's thank god for that

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tupinambis · Posted: Wed Oct 12, 2005 8:31 pm Post subject:

Actually, Slizarus, you're somewhat putting your foot in your mouth. Crotalus durissus are very abundant in South America, along with numerous species of Bothrops. Your average field worker seems to be more scared of the rattlers than most of the other snakes (although I think that's because they have this superstitious snake hierarchy wherein they believe all snakes will eventually become rattlers). And unlike a lot of the North American Crotalids, they aren't small. We have quite a few that would gladly swallow a 5kg tegu and go back for seconds, if it weren't for the fact that they tend to prefer endothermic prey.

As for it piercing the skin, I have little doubt it can, especially on younger tegus. However, for the typical surprise strike, I'd give an adult tegu a 50-50 chance of escaping unenvenomed. Not great, but better than us squishy pink things.

Slizarus · Posted: Wed Oct 12, 2005 9:15 pm Post subject:

alex · Valued Member Joined: Aug 03, 2005 Posts: 106

Ha, snake taxonomy is ever-shifting, particularly in the caenophidians. Generally, Elapidae encompasses or is considered a very close taxon to the Hydrophiinae, which are sea snakes, and consists of corals, cobras, kraits, rinkhals, etc. Exactly what sea snake is a krait or a cobra is a big mess. Good luck sorting it out, I have trouble keeping my colubrids straight at the moment and want to remember that more. Viperidae are vipers, with two major subfamilies Viperinae (vipers) and Crotalinae which are pit vipers - be they terrestrial (i.e. Bothrops, Crotalus) or arboreal (i.e. Trimeresurus if I spelled it right, I like sticking extra syllables in). There's also a third family Azemiopinae, if you ever see a Fea's viper which is just kind of weird and colubrid-like. Basically pit vipers have loreal pits... true vipers don't. Fea's viper is weird.
Caenophidia (for completeness sake) also includes the Acrochordidae (pretty damn arguable where this odd fully aquatic family fits in), Atractaspididae (mole vipers or stiletto snakes), and the big ugly mess that is currently Colubridae, which is really every other snake that no one knows how to classify, and likely is several separate families. I'm pretty sure several full families were just elevated, including Homolopsidae, Heterodontidae, Xenodontidae, etc... I think natricines are also a full family now. Many non-venomous snakes (which are traditional colubrids) now are becoming more and more like cobras without potent venom or good delivery systems.
I like snake taxonomy.
Colin didn't say that C. durissus not only has a reputation for getting quite large, they're also one of the more aggressive and significantly venomous rattlesnake species.

Slizarus · Posted: Wed Oct 12, 2005 10:56 pm Post subject:

I don't even touch Colubrids for those reasons alone, Thanks a lot!

God, I got to stop reading 20-50 year old books, I could have sworn that Crotalids were a family apart, and the Corals/Sea Snakes, I should have known that part.. but all of the literature.. once again stated that they were in the same family.

I love and hate Taxonomy.. You'd think it would be easy to say what species is a species.. and then you get into natural morphs.. localities.. sub species.. misinformation.. common names.. "Rediscoveries"...

I feel real sorry for the guys sorting that out, the debates must be outrageous.

Someone needs to go back and update some of the older books, the old books I read at various libraries are great, but it leads to confusions such as what lead me to the mistake today.

*sigh* Oh well, maybe in the future, we'll have computers sort things out through blood samples and DNA checks... and leave the herpetoculturists time to bicker about something else.. like UV, necessary or not?
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alex · Valued Member Joined: Aug 03, 2005 Posts: 106

Why do you think it would be easy to say what a species is? It's an entirely artificial designation put on biological forms by our pattern-forming little monkey brain. Despite what you probably get taught in high school, there is no agreed-upon definition of a species that works in all cases, and I find the pet trade in any form is detrimental to figuring that out.
I really doubt too DNA analysis is going to fix anything. It's a fantastic tool that leads to a lot of information especially as colour, pattern, location, etc are not particularly great for defining species, but again there has to be agreement to how to define a certain distance as a new species or even subspecies, and I can't see a way that that would hold up for all animals - plants, bacteria, fungi, protists, invertebrates, let alone chordates. Since subspecies are generally geographic variants of a species, would subspecies be based on morphology alone and species as genetics? Admittedly, I stopped taking genetics to any significant extent after my BSc, but I think life is far more complex and adaptable than we are capable of sorting into very narrow catagories.
Also, really stop reading old books (and Reptiles.... I used to love that magazine, and then I think it got pretty crappy as far as my interests were concerned) without tempering it with modern sources. There are a lot of good updated herp books, and you can find a lot on literature searches. Universities generally sell library cards, even if you're not in one, and that's really what you need to keep up to date.
It's 6:30 am my time, and this currently seems lucid.

drfish · Posted: Thu Oct 13, 2005 9:07 am Post subject:

Man, how many dictionaries do you need to be able to eat in a day to talk like that. Very impressive Alex. I will now consult my ever growing translation table for more precise and simpleton terms, lol.

Slizarus · Posted: Thu Oct 13, 2005 9:17 am Post subject:

I'm but in high school myself, and it was unwise of me to say that it would be easy. However I'm not quite sure how you see the pet trade as entirely detrimental to it, it does muddle things up.. quite considerably in a number of cases, but do we not make our own observations? Record data on a species as far as habits, color, pattern, hell, we even count the bloody scales, and then later compare this with what the researchers report in the wild, perhaps finally giving confirmation on whether this animal is truly the animal we've always thought it was, or something completely different?

I have no access to university books, even less so in my location, I'm no longer in the big city much to my distaste, I do my best to back things up with modern texts, but unless it's a book I find particularly usefull to me, I don't have the money to buy it. As far as the internet is concerned, it's grand but so much of it contradicts itself constantly, things are still being decided by people.. and what's taken as solid fact could just as easily be shoved away as a complete lie.

DNA Analysis.. that was just wistfull thinking based on the few books regarding biochemistry and genetics which I've been reading lately like "The Lives to Come"

And as I said earlier.. you get into so many different things.. morphs, subspecies, localities which often amount to the same things.. that it's real bloody hard to get anywhere without a lot of observation from a lot of different researchers, which may just conflict each other in the process.
Perhaps easy in comparison to inventing the first electron microscope, but we already have one of those, and are no closer with herps.

As far as reptiles magazine is concerned.. it's a nice thing, great pictures, reports on care and breeding.. but it doesn't go into the most detailed things.. it's not a science journal, it's just a magazine for a rack.

And aye, you came by quite clear.. which is all I can hope to be.. I just woke up, and I need to get to school! Bah.
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tupinambis · Posted: Thu Oct 13, 2005 10:38 am Post subject:

Ah, how does the pet trade become detrimental towards herpetology? Let me count the ways.......

Whereas you are certainly true that there are some hobbyists out there that are very observant, well trained, make controlled experiments and actually report their findings in a reasonable manner, I'd have to say that for every single one of these, there are at least a million who are the opposite. Some hobbyists have greatly helped the field of herpetology, and without their input, certain areas would be far behind.

In the particular field of tegus, I can show you two very famous examples of both. First, Bert Langerwerf of Agama International. Here's a guy that has really looked into the natural history of the animals he breeds, is relatively well versed in the literature, and as far as I can see, hasn't done anything all that detrimental. His info is usually rock solid and he often goes out of his way to accomodate and inform people. His book, despite being in German, is quite informative even to scientists. This guy is first class and has all my respect.

Then there's the other side, the other famous breeder(s), the St. Pierre's. I will grant that the St. Pierre's have generally excellent quality tegus and their husbandry is usually top notch. That's about as far as I will credit them. They got their hands on some tegus years ago that to their unexperienced eye looked different and so they pushed it as either a whole new species, or a subspecies of T.teguixin (I'm talking about blues here). To anyone thoroughly familiar with the currently recognized species, there is a Dorito's chance at fat camp that the blue is a subspecies of T.teguixin. When I inquired as to how they had come to this conclusion, had they checked the blue's morphometrics with those of the other species (ie. how scientists go about comparing which species is which), Stella's response was "we don't do that". Leaving Ron out of the picture, Stella's approach to anything is reactionary and close-minded. I've rarely seen someone who claims to be so "informed and scientific" that is so far from such a state. To her, if it happens once, it will always happen. By her logic, we should have all won the lottery by now. Any scientists that are familiar with the tegu species, upon looking at a blue, will claim it is T.merianae. But because the St.Pierre's are so respected by the hobbyist industry, everyone takes their word as gospel and now there's this following of people that truly believe the blues are a species that dumb scientists haven't found yet. I'm not saying scientists are infallible, nor do we know all the species of animals there are in the world. But if I get up in the morning, see that the sky isn't blue and deduce from it that the world is ending, I'd be a lunatic. Yet this is pretty much what the St. Pierre's do, and get away with it. They further go about promoting husbandry protocols that are unfounded and in many cases detrimental in certain circumstances. On kingsnake.com, in response to one poster's querie as to replicating the tegu's natural diet, Stella basically said she had tried it, it had made her animals ill, so her conclusion was basically that their natural diet was unhealthy. Jeez, if that were so, then natural selection would have basically wiped out tegus a long time ago, instead of allowing them to disperse across the entire South American continent. Enough of this particular rant....

Then there's the practice of cross breeding species. For something like tegus, to cross breed them in the northern hemisphere seems rather interesting and harmless. Plus, it's on such a small scale, its ramifications are probably miniscule. However, take this same phenomenon with snakes, where cross breeding is rampant and regularly promoted, that to a sane person it should seem as a nightmare. If even ONE of these hybrids escapes, and gets back into the natural population, and successfully breeds, the damage done is incalculable. Such an event will have totally destroyed the genetic identity of those species, will have derailed the direction of countless eons of evolution, will invalidate ANY AND ALL future studies looking at the population genetics and species specific characters. Put simply, cross breeding species is morally reprehensible, unethical and dangerous AT BEST. But a lot of hobbyists go about doing so without a care in the world or even stop once to think about what it could mean, other than how many dollars such a venture would glean for them.

Then there's the simple case of where entire natural populations have been wiped out by collectors. In the past where the naivete of people thinking the resources of nature were boundless and unshakeable, their actions could almost be forgiven. In the modern world where we know better, are fully cognisant of the fact that our simple carelessness could irreversibly erase a species from the planet, collecting endangered species for the simple return of a few bucks is atrocious. You'd probably be shocked by how many times a researcher has been approached by a collector with the "generous" offer of a few dollars if they'll only divest the information of where their study site of a critically endangered species was located.

I apologize for this post seeming all doom and gloom, not all hobbyists are this way, far from it. However, as long as hobbyists blithely go around being unresponsible, uncaring about how their hobby impacts things, then they will be having an even greater detrimental affect on things than a single, ill-determined individual. I'm all for people properly keeping reptiles and other exotics, I started out that way myself. But without responsible and ethical practices, the hobby can be immensely detrimental. For every Slizarus out there that, like you say, counts scales, does the reading, really looks into the proper husbandry of their animals, how many individuals do you think merely got their first reptile because it was "cool", and didn't do any more research other than ask the pet store clerk what it ate? I worked in the pet trade for a decade, and let me tell you, it isn't one to one, or two to one. I don't even think it's twenty to one. It's one of the many reasons I got out of the pet trade.

Slizarus · Posted: Thu Oct 13, 2005 4:03 pm Post subject:

You've got a definate point about the escaping hybrids.. I'll admit I had not thought of that one, and although I admittingly enjoy seeing the appearance and what is produced by such hybrids.. I would rather destroy one I paid $1000's for than let it into the wild, but despite it all.. there are plenty of hybrids out there, that cost little, are common, and if let out, could cause just as much damage as that rare hybrid... and for all we know, it could have already occured in native populations of Milks, Kings, Corns.. even venturing to South America with the boas.

I'm an extremely curious person, and if a hybrid is possible.. I will goggle at the results, see what makes it different.. the traits of both parents.
God knows I do this kind of work daily in Carnivorous Plants, or atleast I did before I came to the sunspot known as Bakersfield Cali.
Crossing.. keeping track of hybrids.. I love it.

But although I'm not a great lover of Genetic purity in humans (Some people are just a bit too picky) I do go along with a number of people who oppose captive hybridization, not because I don't love the hybrids too..it's more on the fact that I don't want a pure locality or species/ssp wiped out and replaced by a mixed little mutt with no other origins than "US" "Europe", etc.
There's just too many unique things.. just delving into my favorite snake, the Boa Constrictor can show you facts of that.. Surinames with their bright tails, thin saddles, and light skin.. The Argentines with their fighting attitude, Almost black pigmentation all on their body, making them seem more of a speckled viper than any Boa.. And Hogg Islands.. a locality so rare, it's thought to be extinct in the wild, and thanks to it's natural Hypo, it's very possible that unless there are more breeders keep the line pure, every one of them is going to have some difference, some het, that even if it's not visible.. is still there, and may manifest in generations to come. And considering that they're no longer available outside captive, you can't just pick more of them up to bring in new blood lines

http://www.boa-constrictors.com/com/com.html

Extremely useful site, especially around the topic of hybrids and inbreeding.

As for the rest of it.. those people who picked herps up because they thought it was cool.. well, I'm sure a lot of us were like that at one point, with the majority of those doing their heavy research right before or after the aquisition of their first reptile.
And for those who have done little research, or haven't much clue about reptiles at all.. that's one thing I'm trying to stave off by going to herp exhibits, participating, setting up displays.. every year we're the most popular group in the street fairs, the museum shows.
Answering questions, promoting awareness.. we can do little about the retailer's ignorance up front, but maybe we can do something about the average individual.
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alex · Valued Member Joined: Aug 03, 2005 Posts: 106

It's just as detrimental to go the other way though - to breed for locality specific pure animals. I'm sure the reproductive issues of greybanded kings is influenced by people who actually breed them based on the mile marker of highway near where they are found. Look at the DISGUSTING degree of exophthalmia perpetuated in leucistic texas ratsnakes, which is often jovially referred to as bug-eyed. I don't even want to touch the abhorrent things we've done to wolves to make, for example, a collie which can be deaf, have colobomas and retinal detachment to the point of bilateral blindness since birth (pretty much all collie dogs are born blind, only some of them can resolve), missing channels in their brain making them susceptible to certain chemicals, and an assortment of inherited predispositions to cancer - this in my mind does not equal the value of having what looks like a classic sheltie. I've often said if I bought a boxer puppy, I'd put it down right away and save myself the bother and heartache in a few years of the horrible way it's going to die. Do you think selective breeding of tegus or any other animal won't lead to the same effects? Keep "blue" tegus or the white-nosed strains different from the rest of T. merianae and see what pops up.
And again, this is where determining what is a species comes into play - you can also make hybrids unintentionally unless you understand what a species is - creamsicle cornsnakes are probably a prime example.
Really, propagating any animal by what you think is desirable is not going to be ultimately the healthiest thing for the species as a whole. We keep alive animals that should die at a young age in the wild, and undesirable traits accumulate rapidly, can be induced rapidly with altered thresholds due to assortment or environmental factors... and then you introduce hobbyists that tend to try to classify what they're seeing with no basis for it at all, or gloss over the faults (not specifically picking on herp keepers, again, DOGS! Do you honestly think that people who developed bulldogs for fighting were unaware the things periodically choke on their own pharyngeal tissue?) and it compounds the situation.[/u]

Slizarus · Posted: Thu Oct 13, 2005 7:50 pm Post subject:

Aye.. inbreeding.. Although you might check the Boa constrictor site Alex about inbreeding...
Though, I do agree with you.. it's disgusting, it really is.. and I would not touch those rat snakes with a pole... the ones who seem to be scaleless..
And transparent bearded dragons? Dear monstrosities, what is that?

By comparison, mutts are healthier and possibly better suited to adaptation..
it's a delicate balance.. that I really don't want to upset.. *shudder*
It's a huge reason that while I want to do a bit of breeding herps in my life.. I'll stick to plants and insects for experimentation with inbreeding and hybridization.. while it's surely possible bad things can happen because of it.. I don't have much of a plan to sell them or release them

And those few CP's with beautiful traits that I may produce in the future.. are going to be registered immediately and will only be sold if they prove to be sterile cultvars/hybrids.. this won't change much, but cloned plants who can't reproduce any other way that splitting won't take over the world..
I hope.
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