from Above or Below?
following text is part of a discussion on the IguanaDen List about heat
from above versus heat from below. Text in italics is from Christina,
responses are by Veronica.
was thinking, in their natural habitat, do iggy's not warm themselves
on rocks and absorb heat from them as well as the sun above? Would that
not be similiar to what I'm proposing?
**No...in their original, natural habitat, they sun themselves from
the canopies of the trees. Coming down to the forest/jungle floor is
asking to be eaten so they limit this action for laying eggs mainly.
Absorbing heat from above is how they've adapted over the milennia.
They have adapted to life as a heliotherm - which means to bask in warm
air rather than "plastering themselves to hot surfaces" (Melissa
Kaplan's words)...or being thigmothermic.
Other than the
risks of injuries, etc. can someone tell me healthwise what does having
heat come from above as opposed to below do? If it affects their digestion,
etc, can you tell me how? I'm one of those people, I really like knowing
the why's of everything.
**Igs cannot feel bottom heat the same way we can...or other reptiles
that DO rely on ground heat like many other lizards, snakes and turtles
do. The nerves have devolved into a minimal number of sensory collectors.
Their circulatory system depends so much on the air around them they
have lost the ability to feel how hot something gets on their bellies...like
a malfunctioniung heat rock.
All they know is that they feel the heat, but by the time the warm blood
circulates to the top of the ig it is cold again making them stay on
the bottom heat source in a futile attempt to get warm. The igs internal,
or core, temperature never gets to the proper temps for ideal bodily
functions which include, but not limiting to, proper food digestion
(ranging from the proper mineral and vitamin dispersion/absorption to
eliminating wastes), mood changes (mostly irritable and depressed),
and the belly heat actually cooking the foods inside the igs' stomach
creating a whole set of problems there.
Melissa Kaplan has a good piece in her book (Iguanas for Dummies)
that explains a bit about the different presentations the igs use with
their body when basking, or when it's time to cool down. This is where
she gets into the smaller piece on being a heliotherm (pg. 66).Hatfield
(Green Iguana Ultimate Owner's Manual) also goes into the different
presentaions the ig will use in order to get the maximum efficiency
from the heat emitted from overhead. This heat would come from whatever
overhead would be available, sun, CHE or basking bulb.