More lizard families than previously believed are venomous

Study shows more to a lizard bite than a nasty nip By Wendel Broere

More lizard families than previously believed are venomous, including several species that are popular pets, scientists said on Wednesday.

Until now, pain and swelling from lizard bites assumed to be non-venomous were attributed to the bacteria that thrive on bits of meat left between their teeth from their scavenging diet.

However, the symptoms are actually from the venom, a finding which could have implications for medical research, said Dr. Bryan Fry of the University of Melbourne, lead author of the research published online by the science journal Nature.

"The venom is the perfect knock-out punch by monitor lizards to their prey like small mammals and lizards," he told Reuters. It stops blood clotting, rapidly drops blood pressure and heightens the feeling of bite pain.

His team of international scientists isolated crotamine -- the classic venom of rattlesnakes whose bite can be fatal to humans -- in the eastern bearded dragon, a popular pet.

However, the bearded dragon's delivery system is primitive and it is present in such small amounts it would not harm a human.

Fry said Indonesia's Komodo dragon -- the world's largest lizard, weighing up to 350 lbs (160 kg) -- was also venomous.

MEDICINES

It had previously been thought that only two families of reptiles were known to have venom systems -- advanced snakes and Helodermatid lizards.

This study demonstrates there are venom toxins in two more lizard families: monitor lizards, such as the Komodo dragon, and iguania such as the bearded dragon and green iguana, but their toxin secreting glands are smaller than those of snakes.

The study effectively doubles the number of potentially venomous reptile species to 4,600 from 2,300.

"There are so many more reptiles with venom now than we previously thought. That fact itself has massive implications for a vast array of areas, whether it be evolution, drug design and development or ecology," Fry said.

Snake toxins are already widely used in medicines to treat epilepsy, haemophilia and thrombosis. The new lizard venom toxins and their molecules present a huge unexplored resource for drug design and development, according to the researchers.

"Milking the big monitors was quite simple, just gently squeezing the glands would result in 40-50 milligrams (dry weight) of liquid venom pooling at the base of the teeth," Fry said.

This means a big Komodo dragon could have more than 200 milligrams ready to delivery at any time, he said.

Fry was anxious that lizard owners should not be unduly concerned by the findings.

"If you're dinner then the venom plays a role, but if you're human it's most likely just to make your hand throb. We don't want people to suddenly be afraid of their pets," he said.

"Nor do we want any silly laws being passed against the keeping of these lizards."

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This is very interesting stuff for sure. Click here to see the original article by Dr. Fry (dial-up warning - 3 MB).

ARE bearded dragons Iguania?
I have been under the impression that Iguanids and Agamids separated from common ancestors a loooong time ago. Being no more closely related to one another than either is to any other lizard family.

Remember the thread where a fauna member was bitten by a savanna monitor (I believe) and he had a serious reaction. So serious in fact that he ended up going to an Emergency room? I think this happened in September of this year. Maybe this is what precipitated that reaction.

Originally Posted by coyote

ARE bearded dragons Iguania?
I have been under the impression that Iguanids and Agamids separated from common ancestors a loooong time ago. Being no more closely related to one another than either is to any other lizard family.

Remember the thread where a fauna member was bitten by a savanna monitor (I believe) and he had a serious reaction. So serious in fact that he ended up going to an Emergency room? I think this happened in September of this year. Maybe this is what precipitated that reaction.

I remember that thread. This does bring up interesting new theories as to why he had the reaction he did. I would like to see what else they discover if they decide to take their studies even further.

It was trpnbils

http://www.faunaclassifieds.com/foru...ad.php?t=72266

Originally Posted by coyote

ARE bearded dragons Iguania?
I have been under the impression that Iguanids and Agamids separated from common ancestors a loooong time ago. Being no more closely related to one another than either is to any other lizard family.

Remember the thread where a fauna member was bitten by a savanna monitor (I believe) and he had a serious reaction. So serious in fact that he ended up going to an Emergency room? I think this happened in September of this year. Maybe this is what precipitated that reaction.

Very interesting article...

Here's something I found regarding the relationship between Iguanids and Agamids...Granted, it was taken from a caresheet by Melissa Kaplan...in the paragraph after this one she talks about how Iguanids come from a "rainless or essentially rainless" area of the world, so maybe take this with a grain of salt:

[quote]Iguanids may be distantly related to the Old World agamid species, which includes such lizards as the Northern African and Middle Eastern spiny-tailed, or dab, lizards (Uromastyx spp.) and the Philippine and Chinese water dragons (Physignathus spp.). Whether iguanids evolved from agamids, or agamids from iguanids, or whether they are a classic example of convergent evolution, is still a matter of debate."


Although I don't have the monitor that bit me anymore (traded it in for a nice BCI), it'll still take some consideration on my part before I handle a Savannah again. But I still handle water dragons, beardies, and large prehensile-tailed skinks (which, from what I understand, sometimes cause severe reactions from their bite) on a daily basis at work without thinking twice about it.

I don't know if what was mentioned in this article had anything to with what happened to me, but I asked around on several forums and took a LOT of strongly worded, highly opinionated, and accusatory s**t for even suggesting that what happened was even remotely related to the bite (none greater than on Kingsuck.com, which is why you won't find me there anymore). Although I only have basic knowledge of the medical end of all of this, anaphylactic shock was the major problem when I got bit...which suggests an allergic reaction. Wouldn't venom, even "mild" venom like what's mentioned here, cause a different kind of reaction? I did find probably half a dozen other people that had reactions to skink and monitor bites, and their stories all sounded very similar to mine, but none of us could draw any conclusions from it.

Regardless of whether it's related or not, I'm interested to see where this research goes. Thanks for the heads-up Coyote!

Originally Posted by TrpnBils

. Although I only have basic knowledge of the medical end of all of this, anaphylactic shock was the major problem when I got bit...which suggests an allergic reaction. Wouldn't venom, even "mild" venom like what's mentioned here, cause a different kind of reaction? I did find probably half a dozen other people that had reactions to skink and monitor bites, and their stories all sounded very similar to mine, but none of us could draw any conclusions from it.

Regardless of whether it's related or not, I'm interested to see where this research goes. Thanks for the heads-up Coyote!

Don't bee stings cause this also? They sting, you get envenomated, and granted it is an allergic reaction to the bee venom, but it is still caused by a venom.
At least from what I know. Like you, I know little about the medical end.

Great post. I for one, being inthralled with venomous creatures my whole life, find this very interesting. I would defenately like to follow these studies to their end.


Ciao,
Rick

Originally Posted by crotalusadamanteus

I would defenately like to follow these studies to their end.

Then hold on to your hat. Dr. Fry is looking at at least one group of PYTHONS as being venomous. That report will be released next year.

Wait a second, this thread accuses Komodo dragons of being venomous when science says otherwise. We KNOW it's bacterea in he mouth with them, research on both it and the wounds infected by it has been done how many times? And I find it hard to believe a lot of these lizards could be venomous anyway... No rivets in the teeth.

We know that venomouse lizards like gila monsters have rivets in their teeth that the venom runs down, and you can still see where the venom comes out in the fangs of venomous snakes. Where is the venom supposed to come from in say... An eastern bearded dragon's mouth? Is it just supposed to drool it out?

Originally Posted by DibDip

Where is the venom supposed to come from in say... An eastern bearded dragon's mouth? Is it just supposed to drool it out?

That is pretty much what the article implies, yes.