PARTHOGENESIS OR PARTHENOGENESIS is the phenomenon that occurs in invertebrate organisms such as invertebrate arthropods and some vertebrate fish, including—rarely—sharks, by which an egg can develop into an adult organism without fertilization. Parthenogenesis can occur naturally or be induced by chemical or mechanical stimuli. These stimuli are believed to simulate the action of a sperm penetrating the ovum, which, even without the sequential addition of genetic material to combine with that of the ovum, can stimulate cell division and embryogen—esis. Parthenogenesis rarely occurs in vertebrates under natural circumstances. When it is induced in organisms higher than arthropods, often the resulting development is retarded, incomplete, or otherwise abnormal.

Parthenogenesis is not the process by which hermaphroditic species self—fertilize. These species have both male and female sexual organs ...