Physiology: Animal Function and Reproduction


How do animals show sexual readiness?

Unlike female humans, most female mammals have an estrous cycle instead of a menstrual one. Around the time of ovulation, these females experience estrus, a period of sexual receptivity. Sexual readiness can be advertised in a variety of ways, including physical and behavioral changes. Among females in species with estrus, it is common to see a swelling of the external genitalia. Female chimpanzees and other primates demonstrate this phenomenon. Male mandrills exhibit sexual maturity and dominance by the vibrancy of the coloration on their facial ridges and posterior flesh. When male elephants reach sexual maturity, they experience a condition typified by leakage of fluid from the penis as well as oozing of “tears” from the face (called musth). Of course, members of both sexes are likely to also exhibit changes in behavior, actively seeking out the opposite sex, for example. Cats and dogs in heat will go to extraordinary lengths to meet a potential mate.


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