Snakes are generally known for being unable to control their own body temperature and for being terrible parents. But by these standards, the reticulated python of Southeast Asia is terrible at being a snake. Rather than laying a clutch and leaving, like most snakes, the python curls around the eggs and incubates them until they hatch. To keep her babies warm, the mother will rapidly vibrate her muscles in order to increase her body temperature to up to 7 degrees above the ambient temperature -essentially, making herself shiver.
Unsurprisingly, sitting on her eggs and shivering without eating takes its toll. In fact, the mother may lose half of her body weight and may not be able to lay another clutch for another 2-3 years. But the evolutionary payoff of having two-foot-long babies crawl out of their eggs, ready to dominate the jungle is certainly worth the short period of suffering.
Learn more about these fascinating pythons and other weirdly wonderful critters on the Quantum Biologist.