Author: Dr. Root Gorelick – Professor, Biology, Carleton University

Not all species need sperm to fertilize an egg for sexual reproduction. Some species need sperm in order to induce completion of egg nucleus development, but then never use the sperm’s DNA. I describe how this self-sexual reproduction occurs in many animals, including some insects, molluscs, fish, amphibians and reptiles, but not mammals.

People have long understood that ejaculate is needed for human pregnancy, but did not understand much more. In the late 1600s, the Dutch scientist Antonie van Leeuwenhoek, who was one of the first microbiologists, thought his own sperm were parasites.