Stay Cool And Eat Bamboo

Pandas can survive on a diet of bamboo thanks to their exceptionally low metabolic rate, scientists say.

AsianScientist (Jul. 22, 2015) – Research by scientists from the Chinese Academy of Sciences (CAS), the Beijing Zoo and the University of Aberdeen shows that pandas are cool, quite literally. Their research, published in Science, was based on the metabolism of both captive and free-living pandas.

Pandas in the wild, of which there are only about 2,000 left, eat a diet consisting almost entirely of bamboo. However, while the giant panda is no longer carnivorous, its gut remains essentially designed for digesting meat. Since bamboo is not easy to digest, pandas must eat up to 50 lbs. of bamboo a day to survive.

Scientists have long suspected that pandas must have low metabolic rates in order to achieve an energy balance. Up until now, however, no one has managed to measure pandas’ metabolism. The current research, which measured the metabolism of pandas both in the wild and in captivity, shows that panda metabolism is incredibly low, about the same as a sloth. In comparison with humans, pandas use far less energy. For example, a 90kg panda expends less than half the energy of a human of the same weight.

How do pandas achieve such low metabolic rates? There are several contributing factors. First, pandas are very frugal in the energy they expend on physical activity. By using GPS loggers attached to free-ranging wild pandas, the study showed that pandas rested for more than half the day and on average travelled just 20 meters per hour.

Thermal image of giant panda. Credit: Nie Yonggang.
Thermal image of giant panda. Credit: Nie Yonggang.

But low activity is only half the story. The metabolic rate of an ‘active’ panda is even lower than a completely stationary human. The secret to the low metabolism of the panda is that the animals have very low levels of thyroid hormones, which is probably linked to a unique mutation in a gene that is critical for thyroid hormone synthesis. This may be instrumental in lowering not only their activity, but also their resting metabolism.

One problem with having such a low metabolic rate is maintaining body heat. The answer lies in the panda’s exceptionally thick fur, which traps its meager body heat. This means the surface temperature of pandas, measured using a thermal camera, is much lower than other black and white animals like zebras and Dalmatian dogs.

The article can be found at: Nie et al. (2015) Exceptionally Low Daily Energy Expenditure in the Bamboo-Eating Giant Panda.


Source: Chinese Academy of Sciences.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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