While most mammals do nurse from their mothers, there are a few exceptions:
* Monotremes (e.g., echidnas and platypuses): These mammals lay eggs and do not have nipples. Instead, they secrete milk from specialized glands in their abdomen and the young lick it up.
* Some marsupials: While most marsupials nurse their young, some species like the bandicoot, have a short lactation period and the young are weaned relatively quickly.
It's important to remember that even in mammals that do nurse, the duration of breastfeeding can vary greatly depending on the species. Some mammals, like humans, nurse their young for extended periods, while others wean their offspring relatively quickly.