As in all other matters sexual there is immense variation throughout the animal kingdom in the actual duration of the coital act. In fact intercourse can range from a few seconds to many hours. Copulating snakes typically remain in union for one or two hours or for much longer periods - there is a suggestion that six to twelve hours is average. The record is held by a pair of rattlesnakes who remained in copulatory connection for no less than 22¾ hours. Such long periods may in part be explained by the difficulty the male has, on account of his spiked penis, in getting away! The fluke, Schistosoma heamatobium - with the female eternally living within a fissure in the male's body-has been said to exist in a state of "permanent copulation."