Regarding chewing, lizards do chop their food as they manipulate it, as
described by Lyle earlier. Though they do not have grinding teeth and thus
do not "chew" in the way that mammals do, they teeth do more than just hold
the food in the mouth. Gecko teeth are good for piercing holes in the
bodies of the prey and, when repeated many times, cutting the prey to the
point that it would likely bleed to death while being swallowed. So, while
a gecko won't chew his food 32 times like we are supposed to, they do use
those teeth and bite the food repeatedly... and isn't that essentially what
chewing is? Biting the food several times before swallowing it.
The only herps I've ever seen swallow live prey without killing or at least
severely wounding it first are garter snakes. Feed a few dozen goldfish to
a garter snake and watch the belly wiggle for an hour or so. eventually the
stomach acids and enzymes kill the prey, as does suffocation. Probably hard
to get good gas exchange in a stomach. With that said, how fast do you
think a mealworm dies in water? Gas exchange through spiracles and the
tracheal system is rather poor if they are wet. Now, add to that the fact
that the liquid in a stomach has an average pH of 2.0 (assuming reptiles are
similar to mammals). If it makes its way into the tracheal system of an
insect (nothing to prevent that from happening, the openings are just holes
in the exoskeleton) then the acid should kill the prey animal quickly. A pH
of 2.0 can dissolve iron nails, if given enough time. Though it may not be
able to completely break down the exoskeleton of an insect (in the given
time at least) it can surely kill the insect... at least by drowning it.
Another thought hinted at on this list: insectivorous lizards eat
insects.... even in the wild. They have been doing so since the time of the
Dinosaurs. I suspect that if they were not adapted to do so without
somebody there to chop the bug's head off or grind it into a paste, then
lizards would have become extinct long before the first TFH book was
published.
Greg
--
Gregory J. Watkins-Colwell
Dept. of Biology
Sacred Heart University
5151 Park Avenue
Fairfield, CT 06432
and
Yale Peabody Museum
Dept. of Vertebrate Zoology
170 Whitney Ave
PO Box 208118
New Haven, CT 06520-8118
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