Posted by:
Kelly_Haller
at Thu Jun 25 17:37:36 2009 [ Email Message ] [ Show All Posts by Kelly_Haller ]
Blackheaded pythons have been observed physiologically thermoregulating through muscular contractions on a few occasions. It was either Neil Charles or Richard Shine, but they maintained a few wild caught adults many years ago that bred and produced eggs. The females were seen to maintain a steady muscular contraction rate, but not nearly as regular or temperature controlling as P. molurus or other more efficient thermoregulating species. I have not seen any data on Woma's, but if Blackheaded pythons can, it would not be a big jump to find out that Woma's have the ability as well.
The behavioral thermoregulation, or basking, that you are seeing is most common with the smaller python species as they don't have the body mass to be able to afford to expend the energy required for true physiological thermoregulation. Aspidites and Morelia are medium size python species and they have a slightly different strategy than the larger thermoregulating species that can afford to expend the energy required for true, full time thermoregulation. These medium size species will use the much energy cheaper behavioral thermoregulation when at all possible before having to resort to the much more energy expensive physiological thermoregulation. This is why you rarely see these species actively thermoregulate by muscular contraction in captivity because keepers control the ambient temp 24/7 and keep it close to the preferred incubation temp. If the cage temp never falls below the mid-80's, these species will not need to physiologically thermoregulate and can usually easily get by with behavioral thermoregulation, or in cases where the temps are in the mid to upper 80's, no thermoregulation at all.
These species would only use physiological thermoregulation in the wild when the temps became too low in the evening and could no longer be compensated for by basking. This switch is limited however, and if the temps get too low, usually by early morning, they shut down altogether and let the egg mass temp drop somewhat. When the sun comes up, they bask again and start the cycle over. The use of burrows by these species gives an obvious insulating effect and helps buffer the low temps at night more effectively. If your cage cooled down enough, you might see the female start up contractions, but I don’t know at what temperature this might be triggered.
Your observations are excellent and show true natural behavior with this species. It also shows that most python species probably naturally incubate their eggs at higher temps than most people think. This is further proven by the fact that for many python species, with a few exceptions, incubation temps below 85 or 86 degrees can cause developmental problems and most do quite well and hatch within maternally incubated timeframes when artificially incubated at 89 to 92 degrees.
Kelly
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Aspidites can actually thermoregulate... - Kelly_Haller, Thu Jun 25 17:37:36 2009
