The mark of Cain spider was first described by the second expedition to Madagascar. It was noted that these spiders seemed to drink blood from around the eyes and ears of the cain - these being the most vulnerable areas of the animal. Some individuals were seen carrying as many as three marks, but it seemed to be more usual to see a cain with a single mark. Though still unproven, the theory goes that a mark will find and eat others of its species when it encounters them outside the mating period (P. rodloxi females may also eat the male after mating).