After eating, snakes become dormant to allow the process of digestion to take place; this is an intense activity, especially after consumption of large prey. In species that feed only sporadically, the entire intestine enters a reduced state between meals to conserve energy. The digestive system is then 'up-regulated' to full capacity within 48 hours of prey consumption. Being ectothermic ("cold-blooded"), the surrounding temperature plays an important role in the digestion process. The ideal temperature for snakes to digest food is . There is a huge amount of metabolic energy involved in a snake's digestion, for example the surface body temperature of the South American rattlesnake ("Crotalus durissus") increases by as much as during the digestive process. If a snake is disturbed after having eaten recently, it will often regurgitate its prey to be able to escape the perceived threat. When undisturbed, the digestive process is highly efficient; the snake's digestive enzymes dissolve and absorb everything but the prey's hair (or feathers) and claws, which are excreted along with waste.