For most animals, sex is an egg-meets-sperm affair that requires both a male and a female. Aptly, this is called sexual reproduction. However, some species have the remarkable ability to reproduce asexually without male fertilization.
Swiss naturalist Charles Bonnet discovered this process, known as parthenogenesis (a Greek term that translates to “virgin origin”), was discovered by the Swiss naturalist Charles Bonnet in the mid 1700s. It was long considered peculiar to plants, insects, and other invertebrates, where it’s relatively common. But in recent decades, biologists have found dozens of cases among fish, reptiles, birds, and even (in special circumstances) the occasional mammal.
Parthenogenesis takes a bewildering number of forms: For some it’s a back-up plan, the last resort when mates are scarce; for others it’s the only way a new generation comes into existence; and still others seem to choose whichever method suits their fancy. Read on to learn which animals have mastered the art of asexual reproduction.