Some baby birds and mammals get plenty of attention from both mom and dad, in part because they are virtually helpless, and sometimes blind, when they are first born. They need plenty of tender loving care. Other offspring, however, are raised by just a single parent. That hardworking mom or dad often makes great sacrifices, such as going without food for long periods of time, in order to provide supper and shelter for the kids.
Some animals spend years with their mother.
Newborn sea turtles, for instance, never know their parents. One answer is that evolution has fine-tuned each species to maximize the survival of offspring. For some organisms, such as many insects and fish, that means putting the majority of parental energy into producing as many eggs as possible, but not caring for the offspring once they hatch. And by foregoing care, they can channel that energy into making more eggs in the next spawning season. On the other hand, some animals, including elephants, many sharks, and people, produce just a few offspring and spend a lot of time and energy helping them survive.