How many stages are involved in complete metamorphosis?

Complete metamorphosis involves four distinct stages: egg, larva, pupa, and adult. This transformation process is a key characteristic of certain insects, such as butterflies, beetles, and flies.

During the egg stage, the organism begins its life cycle, typically laid in a safe environment. Once the egg hatches, it enters the larval stage, where it often looks completely different from the adult form and is mainly focused on feeding and growth. After accumulating enough nutrients and size, the larva enters the pupal stage, where it undergoes a significant transformation within a protective casing. During this pupal stage, the insect undergoes extensive physiological changes. Finally, the adult stage emerges, showcasing the fully developed characteristics of the insect, capable of reproduction, thus completing the cycle.

This clear division into four stages highlights the complexity of insect development compared to simpler life cycles, which may involve fewer stages like those with direct development. Each stage distinctly contributes to the organism's development, with significant morphological and functional changes occurring throughout the process.