Researchers in the United Kingdom were surprised when a fish in the aquarium room at Hull University developed a male sex organ and fertilized her own eggs, producing four offspring.
The cichlid gave birth to 42 more babies during the course of the year, in what the researchers describe as the first documented case of “selfing” which the scientists say is basically having sex with oneself and breeding. The notion of selfing has already been documented with mangrove killifish, but that is the primary way they reproduce. Cichlid reproduction usually requires a male and female fish.
“In the mangrove killifish, selfing is an adaptation,” lead author Ola Svensson told Discovery News. “It is believed that it can be hard for them to find a mate, and selfing is better than not producing at all.”
This event is unique in that the cichlid was both the mother and father of the offspring. “It is a case of sexual reproduction,” Svensson said. While certain animals such as some sharks and reptiles can reproduce via parthenogenesis, this case is different in that the cichlid fertilized her own eggs. In parthenogenesis, there is no fertilization involved.
The resulting offspring were male and female, none of which were capable of selfing. At least not yet.