Why are giant panda cubs so terribly tiny?
Joyce Park stashed this in Science
Panda babies are alarmingly unviable. Why must this be?!?!
Because bears are altricial.
First, the terminology. The key word to remember is "altricial."
“It’s a fancy word that means pretty much helpless," said Don Moore, a senior scientist at the National Zoo and an expert on mammals.
The opposite of altricial is precocial. A chick freshly hatched from the egg is precocial, walking around, eating and peep-peeping up a storm. A human baby, however, emerges on the altricial side of the spectrum.
A giant panda is a bear. Bear cubs are extremely altricial in general. Of the placental mammals, Moore said, the panda has the tiniest babies in comparison to the size of the mother. The size ratio can be as small as 1 to 900.
So why so small? The answer has a lot to do with bamboo.
A giant panda is a creature that has evolved to eat a diet primarily of bamboo, a woody grass that is hard to digest. To adapt to this rather spartan diet, giant pandas have evolved a low metabolism. They sit around a lot. They take the concept of "low key" to an extreme.
This low metabolism means the female's blood-oxygen level is relatively low. That tiny panda cub actually has a better shot at survival if it can breathe fully oxygenated air — and so being outside in the world is better than being inside the mother. Moreover, the kind of fatty acids that the cub needs can't be passed from the mother to the cub through the placental barrier, Moore said.
“In order to get the fatty acids to the baby, to make the baby grow faster, they can't go across the placenta, but they can go out in the milk," Moore said.
Wow!! What a learning. Lovely to know so much about this adorable creature :-) :-)
It's frankly amazing the species still exists. They are poor at breeding and not equipped to survive.
Adorability is their survival strategy.
Adorability is their evolutionary advantage.
>>>Panda babies are alarmingly unviable. Why must this be?!?!<<<
That's what makes Pandas so special!