Most owls are nocturnal or crepuscular birds of prey. There are many diurnal species that exhibit some nocturnal behaviors. American marten may be nocturnal or diurnal. Reports differ as to whether they are diurnal or nocturnal animals. They may considered as nearly nocturnal and diurnal ecological equivalents. They are crepuscular and nocturnal in habits. Duikers can be diurnal, nocturnal, or both. Hamsters are solitary but tend to be nocturnal. Eyesight is a particular characteristic of the owl that aids in nocturnal prey capture. The leopard is elusive, solitary, and largely nocturnal. Ejaculation may occur spontaneously during sleep (known as a nocturnal emission or wet dream). Treatment for paroxysmal nocturnal dyspnea depends on the underlying cause. As in many species of nocturnal birds, they reflect the light of flashlights. Whiskers themselves may have evolved as a response to nocturnal and/or burrowing lifestyle. The majority are detritivorous, with the exception of centipedes, which are chiefly nocturnal predators.