தொல்தமிழர் அறிவியல் –88 : 27. புறா - கல் உண்ணல்
Some animals that lack teeth will swallow stones or grit to aid in fragmenting hard foods. All birds have gizzards, but not all will swallow stones or grit. Those that do employ the following method of chewing:
"A bird swallows small bits of gravel that act as 'teeth' in the gizzard, breaking down hard food such as seeds and thus helping digestion."
These stones are called gizzard stones or gastroliths and usually become round and smooth from the polishing action in the animal's stomach. When too smooth to do their required work, they may be excrete.
---Solomon et al., 2002.
ஈராயிரம் ஆண்டுகளுக்கு முன்னர் வெறுங்கண்ணால் கண்டு கூறப்பட்ட இவ்வரிய செய்தி அறிவியல் ஆய்வுக்குரியது என்று அறிந்து, பதிவு செய்துள்ளமை போற்றுதற்குரியதாகும்.
Doves swallow Pebbles and Stones
“ A passage from Ahananuru (271:1-3) and one more from Pattinap-palai (57-58) specifically mention that doves consume stones ; also swallow pebbles from the dry river-bed. They fly for a long distance in search of suitable pebbles.
Doves eat hard-shelled fruits and seeds. They don’t have teeth to pulverize these hard substances. To get them digested, the doves swallow the stones which would help break and grind the seeds in the gullet.
Similar habit is found in a few other birds such as crow, ducks and everglade kite. They all swallow the food. Even though they have a digestive tract known as gizzard, the birds eat stones also to help them digest earlier and easier. This is what we understand from Wikipedia of the digital age. (General bird care –June 28,2008.)
The fact of the eating habit of birds and their long flight in search of food were also keenly observed by the Sangam poets and incorporated in the anthologies.”—Editor. ------------------தொடரும்.......