Lizards pass through three different life stages, beginning as eggs, hatching into juveniles and ultimately becoming mature adults. Most juveniles resemble miniature versions of the adults, while others experience a change in color or body proportions as they grow. Some lizards pass through all three life stages within the course of one year, while others live long lives, taking many years to hatch and mature into adults.
There are a few exceptions to this pattern of life stages. Some lizards give birth to live lizards, but most of these still experienced an egg stage — it just occurred while they were still inside their mother's body. Such lizards are enclosed in flexible, membranous eggs, which often break as they pass through the mother's vent, instead of hard, calcified eggs. The young of one species develop inside their mother's body while being nourished by a placenta instead of an egg yolk.
Freshly hatched lizards must fend for themselves, as lizard parents do not provide any care to their young. Most young lizards consume insects and other invertebrates; however, as they mature, many species begin consuming increasing amounts of vegetation.
Some lizards, such as five-lined skinks, display different colors as they mature. This is thought to be an adaptation that seeks to maximize the lizards' crypsis as its body size changes.