Six digits

Art360 · Member Joined: Dec 23, 2005 Posts: 35 Location: Tennessee

I just noticed that one of my tegus has a sixth "finger" on her left hand. It is complete with claw and all! Not sure if she has use of it or not. The wierd thing is that I just noticed it, I spend at least an hour with them a day. Is it possible that it just grew out? I'ld like to breed her and see if this trait is genetic or just a random occurrence. Anyone ever seen this in tegus?

hoosier · Posted: Sun Apr 08, 2007 9:40 pm Post subject:

could you post a pic of it?
i dont believe that it could just grow out. it may be just a a rare occurance. but i doubt it would be passed on through breeding, as i dont believe that it could be passed on genetically. like i said though, could you post a pic of it?

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chelvis · Posted: Mon Apr 09, 2007 6:50 pm Post subject:

I originally thought the samething Hoosier thought that the 6th figure wouldn't be a gentic trait and just a stright up mutation. He most likly had it from birth like kids that have an extra thumb. Then i remembered that there is a gentic trait in cats that cuase them to be born with 6 toes on each paw. This is notice most in stray cats on the east cost but is slowly moving west. So i have no clue if its gentic or just a mutation, gentically speacking.

tupinambis · Posted: Mon Apr 09, 2007 8:16 pm Post subject:

The very term mutation implies genetic basis. If it weren't genetically derived, it would be a deformity. There's next to no chance that the toe recently grew out, it almost certainly was born with it and you just hadn't noticed it before. Polydactyly is often genetic and can be passed on to future generations, but it can also be caused by environmental influences during embryo formation such as toxinogens or parasites.

hoosier · Posted: Mon Apr 09, 2007 8:35 pm Post subject:

tupinambis · Posted: Mon Apr 09, 2007 9:17 pm Post subject:

pretty much.

chelvis · Posted: Tue Apr 10, 2007 12:16 am Post subject:

actully resently they found out the multy legged frogs weren't deformed from the chemical run off (although in some cases that is the cause) but from a paricite that feeds on the growth buds of the legs, and other areas of the developing tadpole. Just a little side note. And your right it is a deformity not a mutaion. good thing this isn't a mid term other wise i'd lose some point there, lol.

Rick · Posted: Tue Apr 10, 2007 2:02 am Post subject:

It's called polydactylism. It's actually very common in some species, such as humans and cats. (Ever see a 'double pawed' cat?)

The effects vary. Some have non-functional extra digits, some have fully functioning extra digits. I recently had a baby bearded dragon with 6 toes on three of it's feet. Sadly he died of unrelated issues before I could breed him.

Here is a Gila with a sixth toe..

http://www.visualsunlimited.com/browse/vu441/vu441986.html

If it's an deformity caused during development/incubation it's not going to be genetic, but as stated.. genetic polydactylism is common and is genetic.

1 in every 500 children (humans) are born with polydactylism, but generally the extra digits are removed at birth for cosmetic reasons. I personally know a woman who has 6 toes on each foot. I grew up around this person, saw her barefoot while swimming and such as teens.. and I never even knew. She never made any comments about it and thus never drew my attention to it. Once I did notice, I saw that they were 6 perfectly formed toes. I couldn't even tell you which toe was the 'extra'.

It's actually quite interesting. I personally love this tidbit of info...

"Polydactyly is an ancient trait and but for a quirk of evolution, all modern animals would have 7 or 8 digits instead of just 5. The oldest known four-legged animals, Ichthyostega and Acanthostega, had 7 or 8 digits per limb. The "extra" digits were next to the thumb. The extra digits disappeared 350 million years ago, leaving modern animals with just 5 per limb. 100 million years after evolution opted for five digits, throwbacks to ancestral polydactyly occurred, as a fossil of a seven-toed reptile demonstrates. The fossil, an aquatic marine reptile called Nanchangosaurus, was an mutant or evolutionary throwback which lived 100 million years after other seven-toed amphibians had died out.

Nanchangosaurus lived about 242 million years ago in China. The fossil reveals that it had seven complete digits on its forelimbs and six on its hind limbs. Other fossils didn't have well-preserved digits, so we can't be sure whether polydactyly was a trait of the whole species or if was restricted to a single mutant animals"

Rick
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Art360 · Member Joined: Dec 23, 2005 Posts: 35 Location: Tennessee

Well, glad to get all this info. I'm actually training in Louisiana so I can't take a pic immediately. My wife is taking care of our 18 herps!! LOL. I may get her to take a pic. I was pretty amazed to see this extra digit. I took a triple take and then had to pull her out and examine more closely. A friend of mine had a double pawed cat and most of the kittens had a sixth paw. Only time will tell if this proves genetic. Is that worth money? Regardless I don't hink I could sell her. I'm really sure it did not recently grow out but it's crazy to imagine it took me this long to notice it. Now on my older tegu I check the digits all the time for stuck shed and maybe that's why I have a hard time believing this was here all along. I can't wait to post a pic of her foot it looks crazy.