Drinking
Infants employ a method of suction wherein the lips are pressed tight around a source, as in breastfeeding: a combination of breath and tongue movement creates a vacuum which draws in liquid.
[6] Ruminants and most other herbivores partially submerge the tip of the mouth in order to draw in water by means of a plunging action with the tongue held straight.
[4] In cold and frozen environments, some animals like hares, tree squirrels, and bighorn sheep resort to consuming snow and icicles.
[8] In savannas, the drinking method of giraffes has been a source of speculation for its apparent defiance of gravity; the most recent theory contemplates the animal's long neck functions like a plunger pump.
Most birds are unable to swallow by the "sucking" or "pumping" action of peristalsis in their esophagus (as humans do), and drink by repeatedly raising their heads after filling their mouths to allow the liquid to flow by gravity, a method usually described as "sipping" or "tipping up".
[10][12] In addition, specialized nectar feeders like sunbirds (Nectariniidae) and hummingbirds (Trochilidae) drink by using protrusible grooved or trough-like tongues, and parrots (Psittacidae) lap up water.
[10] Most birds scoop or draw water into the buccal areas of their bills, raising and tilting their heads back to drink.
[15] Amphibians and aquatic animals which live in freshwater do not need to drink: they absorb water steadily through the skin by osmosis.
Lack of hydration causes thirst, a desire to drink which is regulated by the hypothalamus in response to subtle changes in the body's electrolyte levels and blood volume.
[20][21] Evidence-based hydration experts say that the amount of drinking water needed depends on ambient temperature, activity level, body size, and sweat rate.
Most cultures throughout history have incorporated some number of the wide variety of "strong drinks" into their meals, celebrations, ceremonies, toasts and other occasions.
[26] A high rate of consumption can also lead to cirrhosis, gastritis, gout, pancreatitis, hypertension, various forms of cancer, and numerous other illnesses.
