Tarantulas move their jaws vertically, or up and down. The majority of spiders belong to the suborder Labidognatha, or araneomorph spiders, which includes both the hunting spiders and the web spinners. These spiders are easily distinguished from tarantulas because they move their jaws sideways, like a pair of pliers. However, it is necessary for the tarantula to be in a fairly moist environment where the temperature ranges from 75 degrees to 82 degrees Fahrenheit, for there to be successful molting. As a spider nears molting, it becomes more sluggish and stops feeding.
Some spiders flip on their backs to molt, while others lay on their sides.
Under the old exoskeleton has a new, soft skin, and it must struggle to get out of the old. This is a very critical time for the spider. If the conditions aren't just right, the tarantula may split it's new skin. If this happens, the spider could bleed to death. After the molt is complete, the spider is very vulnerable.