Despite spending almost their entire lives underground, and having very poor eyesight, Cape mole-rats exhibit distinct diurnal rhythms in time with the hours of daylight on the surface, and are primarily nocturnal. Unlike some other species of mole-rat, they are solitary animals, and, except when a female is raising young, only one individual inhabits each burrow system. They are highly aggressive towards other members of their own species outside the breeding season. When encountering a rival, they adopt a rigid posture with the head thrown back and jaws open, chattering their teeth and occasionally making short leaps in the direction of their opponent. Because burrow systems can approach within of each other, burrowing animals warn away rivals using sex-specific seismic signals.