To train our tired tongues tremendous tricks
A look at the tongue and an experienced physician can diagnose dermatoses, diabetes, liver ailments, stomach disorders and other diseases quite easily. But the tongue is more than a mirror of our health (and for some people an organ that has to tolerate piercing – a custom dating back to pre-Columbian Amerindian Maya and Aztec cultures). It lets us taste, possesses the best two-point discrimination of any body region, is tremendously sensitive to temperature and most of all it lets us speak. Trying to say “Peter Piper picked a peck of pickled pepper” or “A proper copper coffee pot”, your tongue twists and it twists because of a remarkable arrangement of nerves and longitudinal, transverse, circular, and oblique muscle fibres.
Embryologically, the vertebrate tongue is a bizarre organ derived from four pairs of gill arches. In human beings the front two-thirds of the tongue are of ectodermal like skin and nervous tissue; the proximal third ´(i.e., the back of the tongue) is endodermal like the intestine in origin. So-called circumvallate taste buds (= dome-shaped structures with a moat around), surrounded by ectodermal tissue, are themselves islands of the endoderm. Four different cranial nerves directly attached to the brain are involved in the tongue’s control and its various functions and the bulk of the tongue’s musculature stems from the back region of the skull. To cut a long story short: a really complicated organ.
In toads and salamanders the tongue is sticky and, anchored at the front of the mouth, catapulted out by muscular contractions to hit the prey, a worm, a fly or a beetle perhaps, The tongue of the chameleon is a projectile that is as long as the animal itself. It is sticky and shoots out of the chameleon’s mouth with astonishing speed (0.04 seconds) and accuracy. Woodpeckers, too, have very long tongues and can extrude them as much as five times the length of their beaks. And mammals? Visit the zoo sometime and take a look at how the giraffe uses its nearly half a metre long tongue!
The tongues of mammalian anteaters are also worth mentioning as they may be anchored not in the throat, but at the breastbone to give them extra length. They are cylindrical and sticky and in the Spiny Anteater and the scaly Asian pangolins (now critically endangered) can undergo a kind of erection to stiffen them, because of the vascular spaces within them. And what if there is no tongue at all? The “Aglossa”, a group of South African and South American amphibians (e.g., clawed toads of the genus Xenopus) would say -if they could speak without a tongue- that one can survive quite well without one. But fun with tongue-twisting sentences like those above or this one below would definitely be out: Specifically and swiftly say: Sheila’s six slippery snails slid slowly seaward while she sells silly seashells by the seashore.
© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2019.
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