Geoscience Reference
In-Depth Information
withrespect todinosaurs,ostriches andotherlargeflightless birdsregularly include
rocks on their lists of items to get into their bellies.
However, where this seemingly simple behavioral division of “Oops!” or “I
meant to do that” gets a bit more blurred is when, say, our same alligator purpose-
fullyeatsanotheranimalforameal,butinitseagernessswallowsafewrocksstick-
ing to or just underneath the prey. Even more complicated would be if the alligator
ate another animal with gastroliths inside of it. In either case, this means the gastro-
liths were ingested accidentally, regardless of whether the original gastroliths were
inside or outside of another animal, or biologically or geologically formed. Power-
ful digestive juices inside that alligator then may reduce the body of its prey item,
but the gastroliths might be left behind, a ghostly clue that another animal might
havebeenthere.Ofcourse,wealsodonotknowifthepreyanimalhadaccidentally
or purposely eaten these rocks; all we know is that the rocks were being recycled,
spending time in yet another animal's gut.
Now, it might seem unlikely that an animal would knowingly consume a rock,
but think of how many pet owners fool their pets into taking unwanted pills by
folding these into their food. Once a feeding frenzy starts, all sorts of items might
unintentionally get included and make it into a gullet. Even herbivores could con-
sumerocksthatjusthappentobepartofthesurroundingsoilstickingtoplantroots.
Moreover,animalssometimesmistakerocksforfood.Forexample,snailsinapond
might look just like some of the stones lying along a pond bottom. So a vertebrate
that likes to eat these snails, such as a fish, turtle, or alligator, might just indiscrim-
inatelyingestanythingthatlookslikethosesnails,someofwhichwillberocks.For
thoseofyouwhothink“Iwouldnevermakesuchastupidmistake,”recallallofthe
times your eyes were drawn to brightly colored beads that looked like hard candies
and how tempted you were to pop them in your mouth (and perhaps did). Visual
triggers can be quite powerful, particularly when accentuated by hunger.
All this gastrolith goodness is nice to know, but a nagging question about in-
tentional rock eating should be asked: Why? As in, why would an animal eat a rock
