Millipedes defend themselves through a variety of strategies, including curling up into a tight ball, releasing a noxious chemical secretion, and even playing dead. When a millipede feels threatened, it will curl its body into a tight spiral to protect its soft underbelly and expose its hard exoskeleton. It may also release a foul-smelling and irritating secretion from its glands that can deter predators. Some species of millipedes also have sharp spines on their bodies that can puncture the skin of predators, causing pain and possibly infection. Additionally, millipedes may feign death, remaining motionless until the danger has passed.