Giant pandas are huge. In the wild, adult pandas weigh 80-100 kilograms. In captivity, adult pandas weigh 80-130 kilograms. The largest ones can grow up to 180 kilograms. They look like round, black and white balls. But panda babies are very small when they are born, with an average weight of only about 100 grams. The smallest panda baby born before was 42.8 grams. On July 11, 2019, giant panda "Chengda" was born at the Chengdu Giant Panda Breeding Research Base. For twin sisters, the older sister weighed 171.9 grams at birth, and the younger sister weighed 42.8 grams at birth. This is smaller than the panda cub "Wu Yi" (51 grams) born in 2006, whose weight has already exceeded 130 kilograms after the breeders' careful care. Even the normal weight of a new born panda is about 100 grams, which is pitifully small. The weight comparison between a newborn panda cub and its mother reaches an astonishing 1/900, which is very exaggerated among mammals. The ratio for humans is about 1/22 , the Bengal tiger's ratio is 1/120, the killer whale's ratio is 1/50, the giraffe's ratio is 1/10, and the African elephant's ratio is 1/45.
What is the relationship between the size of mammal newborn calves?
First of all, we can find that the newborn babies of marsupials are relatively small. This is mainly related to their parenting methods. Because of the existence of the pouch, the birth of their offspring is not a true birth. After birth, they can be placed directly in the Secondary feeding is carried out in the pouch, and the cubs can continue to suck milk and grow up in the pouch. Marsupials do not have a true placenta, so their young are born prematurely when they are fully developed and continue to develop in the pouch.
Marsupials are very typical late-maturing animals, and there are also many precocious animals in nature. They have already experienced very complete development in their mothers and can live independently after a short period of time after birth. For example, some ungulate mammals, as an important link in the food chain, face many predators, so they are under great pressure to survive. They need to become independent quickly after birth, so that they will not easily become prey for predators.. For example, giraffes, their babies can weigh about one-tenth of their mother's weight after birth and can stand up and run very well. Giant pandas are not marsupials. The weight of their babies is so small when they are born, which seriously affects their survival rate in the wild. This is also the reason why their numbers have been scarce for a long time.
Why are newborn pandas so small?
Scientists have found that giant panda embryos have delayed implantation. Their fertilized eggs will float in the uterus for a period of time and will not immediately implant and develop. This time generally ranges from 1 to 3 months. Only when the environment When the time is right, the fertilized egg will implant and develop. The gestation period of pandas is generally about 84-160 days, which means that due to the phenomenon of delayed implantation, the actual development time of panda cubs in the womb will be reduced by about half, which is why their newborn panda bears only One of the reasons is about 100 grams.
In the wild, the gestation season of pandas often overlaps with winter. Ursids like to hibernate in this season when food is scarce. They do not eat or drink, and rely mostly on their own stored fat to survive. In order to reduce energy consumption in the mother's body as much as possible, scientists believe that giant pandas choose to give birth to an immature panda baby in order to allow the panda cub to absorb very little energy, and then continue to develop outside the body through milk. Existing research has also found that panda bears have a significant decrease in appetite during pregnancy, and their body intake of nutrients is significantly reduced.