Spider Development
Unlike some insects, which go through larval and pupal stages, spiders change very little as they grow: the young spider resembles a miniature adult. Spiders have their first molt inside the egg sac, after which the pinhead-sized creatures eat their way out. Depending on its size, a spider typically molts (sheds its cuticle) six to eight times between the time it leaves the egg sac and when it reaches adulthood. Molting is a dangerous process. The spider is vulnerable for as much as a whole day, until the new exoskeleton hardens. If a leg is broken off as the spider develops, a new but shorter leg generally appears at the next molt. Spiders can live anywhere from less than a year to more than twenty. Generally, the more evolved the species, the shorter its life span.