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RAUK - Archived Forum - Smooth snakes

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Smooth snakes:
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Chris G-O
Member
Joined: 14 May 2003
No. of posts: 36


View other posts by Chris G-O 		Posted: 27 Sep 2004

Hello all,
I don't see a smooth snake thread here so i'll start one... I have pictures i took of a juvenile smooth snake on Saturday and i notice it has quite a large pit in front of its eyes, larger than the nostrils. I hadn't noticed it before (the wonders of digital photography!) and wondered if it's something that's lost in adults and whether it's akin to the heat-sensitive pits in pit vipers etc.
Tony can you help me??


cheers
Chris

administrator38257.7838194444
Chris Gleed-Owen, Research & Monitoring Officer, The HCT & BHS Research Committee Chair
-LAF
Senior Member
Joined: 03 Apr 2003
No. of posts: 317


View other posts by -LAF 		Posted: 27 Sep 2004
As far as I know thermal pits have only evolved in the Crotalidae and the Boidae. Ironic as these two families are at pretty much opposite ends of the evolutionary tree for snakes. In the Boidae the trait isn't ubiquitous. Wolfgang would be able to confirm this or brand me an idiot.

It would certainly seem strange as...

a) Coronella primarily prey on ectotherms, especially as neonates.

b) To have this organ in juveniles but lose it with age seems unique.

Could a possibility be the loreal scale? These are very small on adult Coronella so, as young snakes have disproportionately large eyes could it be that the preocular is large and well pronounced causing the loreal to be pitted between the preocular and the nasal?

Just a thought, Lee.-LAF38257.7663657407
Lee Fairclough
-LAF
Senior Member
Joined: 03 Apr 2003
No. of posts: 317


View other posts by -LAF 		Posted: 27 Sep 2004
Hi, the picture is now up (wasn't when I posted earlier). From the looks of it I'd say it was certainly just a dimpled loreal scale. Looks like there's a bit of damage on the preocular too. Maybe he/she has had a run-in with something.

Regards, Lee.
Lee Fairclough
Tony Phelps
Forum Specialist
Joined: 09 Mar 2003
No. of posts: 575


View other posts by Tony Phelps 		Posted: 27 Sep 2004
I must say never noticed this before - my guess is a temporary disifigurement that occurred when neo was breaking from pellicle - this can often take some effort and is done with a lot of vigour and can take a long time.

Apart from pitvipers and pythons and boas - some old world vipers have to some degree heat sensors,the supranasal sac situated behind the nostril - particularly particularly well developed in the genus Bitis.

T

Tony

- Smooth snakes

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