Moulting (molting) is a process where a spider sheds off its exoskeleton. The main purpose is to enable the spider to grow though matured female tarantulas moult every year for maintenance purpose. While moulting the spider is in a vulnerable state and cannot defend itself. If moulting is done without adequate space, abnormality might occur with the new skin which might prevent future moult hence resulting in death.

Before moulting, a spider usually withdraw to a retreat and stop feeding. When it is ready to molt, a spider hangs upside down from a thread and the carapace will open. Then the abdomen is liberated and the last stage is taking the legs out. For most spiders, the process lasts between 10-20 minutes but can go for hours for tarantulas.









After undergoing a moult, the spider will rest for a while to adjust with the new skin. Depending on species, a spider moult about 7-9 times before mature. Sexual organs might only be apparent after the last moult and in some species, would be the easiest time to determine gender.