In one of the more startling scientific discoveries of late, two teams of researchers have found that a baby hammerhead born in a Nebraska aquarium six years ago was conceived via parthogenesis—i.e., without the genetic contribution of a male.
New York Times:
But through the analysis “it was pretty clear that there was no male contribution,” said Mahmood S. Shivji, director of the Guy Harvey Research Institute and author of a paper on the finding being published online today by the journal Biology Letters.
Instead, the female shark’s own genetic material combined during the process of cell division that produces an egg. A cell called the secondary oocyte, which contains half the female chromosomes and normally becomes the egg, fused with another cell called the secondary polar body, which contains the identical genetic material.
Robert E. Hueter, director of the Center for Shark Research at the Mote Marine Laboratory in Sarasota, Fla., said the finding helped fill a gap in understanding of parthenogenesis, which has been found to occur in most vertebrate lines except mammals and, until now, cartilaginous fishes like sharks.
“These guys have proven their case,” Dr. Hueter said of the researchers.