What kind of metamorphosis do silverfish and firebrats exhibit?

Silverfish and firebrats undergo a type of development known as primary or ametabolous metamorphosis, which is characterized by no significant transformation between life stages. Instead of going through distinct larval and adult stages like insects that exhibit complete or incomplete metamorphosis, silverfish and firebrats hatch from eggs and gradually develop into adults. Their young resemble adults closely and undergo a series of molts, becoming larger and maturing without undergoing a complete metamorphic change. This means they retain a similar shape throughout their life cycle, just growing larger with each molt.

Understanding the life cycle of silverfish and firebrats as a continuous development helps clarify why ametabolous metamorphosis applies to them, differentiating them from other insect groups that do exhibit more dramatic lifecycle changes, such as butterflies or beetles.