The main thing that sets mammals apart from all the other animal groups, is the fact that the females of each mammalian species have mammary glands. These organs are found only amongst mammals and they produce milk with which the female can feed her young, giving them the best possible start in life. The young suckle on the teats/nipples of their mother in order to consume this nutritious feast.|
However, these milk-producing glands can often mean that the offspring of mammals are much more vulnerable at birth than those of other animal groups, as they rely more heavily on the care and protection of their mother. Some baby mammals are in fact so underdeveloped at birth, that they are born hairless and blind and are often dependent on their parents (mainly mum) for a significant amount of time.
New-born African Elephant calves weigh around 3% of their total adult weight and stand at about 90cm tall. They are known to drink nearly 11.5 litres of milk every day but unlike many other species, it is not just their mother that feeds them, as African Elephant calves are also cared for by other females in the herd. They are generally dependent on their mother for up to 5 years, although some may not be weaned until they are nearly 10 years old.
Baby Hedgehogs on the other hand, are not dependent on their mother for quite so long, but are born without their spikes and they cannot see. By the end of their second week, the Hedgehog pups have spikes and their fur has started to grow, with their eyes also having opened. They are weaned at between 3 and 4 weeks of age, and begin to accompany their mother on foraging trips before they leave the nest and have to fend for themselves.
Koala babies however, are more dependent on their mother as they are born at about an inch in length and weigh less than a gram. As with all marsupials, the female Koala has a pouch on her underside, which the joey crawls into after birth. They are then able to attach themselves to one of two teats inside their mother's pouch, where they remain suckling milk for up to 6 months before they start to venture out.
Cheetah cubs are born blind, hairless and unable to really move at all. The mother suckles and protects between 4 and 6 young for up to 18 months when she eventually abandons them to fend for themselves. Sadly, it thought that up 90% of Cheetah cubs in some parts of Africa don't survive their first three months as they are so helpless and vulnerable. Cheetah cubs weigh less than 300 grammes at birth and measure about 30cm long.
Over in the Far East, generally two Giant Panda cubs are born to their mother but it is very rare that more than one will survive. At birth Giant Panda cubs weigh about the same amount as a mouse and are hairless and blind, generally not opening their eyes until they are nearly two months old. They tend to remain under the watchful guidance of their mother until they are three years old and can venture into the bamboo forests on their own.
As you can see, despite all belonging to the same animal group, species all appear to develop and then care for their young differently, which is often a real struggle for many mammalian mothers around the world. Humans in the west however, have by far the longest dependence on their mothers, leaving home at an average age of between 16 and 18 years old.
Ben the Beaver's Barrel of Laughs