Everyone loves giant pandas! Not just because of their sweet and cuddly nature, but because of the fact that you can stare at them for hours as they devour bamboo plant after bamboo plant. But you may have wondered why these fluffy animals have such an insatiable hunger for bamboo if the low-nutrient plant isn’t actually providing the nourishment it should. A recent study suggests that the giant pandas have lazy lifestyles in order to cleverly conserve energy.
Scientists closely followed the habits of five captive and three wild giant pandas to better understand their lifestyle. They analyzed the amounts of energy that each panda spent on a daily basis and came to the conclusion that they only expended an average of 38% of what would be expected from an animal with the same body mass.
Granted, scientists had already expected that the metabolism of giant panda bears would be low. The surprise, though, is that it was this low. In fact, lead author Fuwen Wei explains that the bamboo-eating animals expend less energy than other animals, such as three-toed sloths or koalas.
So why is the panda bear’s metabolism so low? The explanation lies with the bamboo. The average-sized panda bear would have to eat approximately 83 pounds of bamboo daily to meet their caloric requirements. Yet bamboo is exceptionally low in calories, but very high in fiber, much like celery.
Even if they were to eat as much bamboo, they would still face difficulties moving from one clump of bamboo to the other. As such, their energy expenditures must adapt. Researchers believe that such an exceptionally low energy expenditure is precisely what facilitates the giant panda’s survival on this calorie-deficient diet.
There are certain mammals who have even lower daily energy expenditures. The Australian rock rat, for instance, only expends 21% of its expected energy daily, while the golden mole expends 26%.
The team of researchers used GPS tracking to understand exactly how these energy expenditures are brought to a minimum. For one, giant pandas do not move a lot. If they must go from one place to another, they do so extremely slowly. In fact, researchers found that giant pandas only spent approximately one third of their time moving (this applies in the case of captive pandas, with wild pandas moving a bit more).
Furthermore, the giant panda anatomy has also adapted to their energetic particularities. Relative to their size, panda bears have smaller livers, kidneys and brains as compared to other bears. Smaller organs require less energy to perform its functions.
Thyroid hormone particularities were also identified, as were specific genome mutations involved in the production of thyroid hormones. Panda bears only produce half the amounts of thyroid hormones that other mammals their size produce.
Taken together, all these seemingly random particularities work towards one common goal: that of preserving energy, so that the giant panda may pursue its one love connection: its romance with bamboo.
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