A life cycle is an entire lifespan of an organism: birth, growth, and development into an adult, reproduction, and death of the adult. It is considered a cycle because most adult organisms reproduce new offspring, which keeps the cycle going. Stages of the life cycle vary for different types of organisms. Some undergo major changes where the offspring looks very different from the time it’s born to the time it’s an adult, like a butterfly. Other organisms have offspring that are born with features very similar to the adult, like humans. Some life cycles are short, and some are long. The life cycle of a chicken consists of an egg, embryo, chick, pullet/cockerel, and hen/rooster. On average chickens live 3 to 8 years.