Crocodiles are ectothermic, meaning they regulate their body temperature using external sources. The physics of heat transfer (conduction, convection, and radiation) plays a crucial role in understanding how they regulate their body temperature.
If your interest is in the literal "crack" of a crocodile, recent research has revealed that the scales on a crocodile's head are actually a result of physical cracking rather than genetic patterning. Self-Organizing Scales crocodile physics 17 new crack