A fisherman discovered a two-headed shark fetus in the womb of a bull shark he caught off the Florida Keys.
He then shared the strange fetus with scientists, who confirmed the discovery of the bizarre creature in a new paper.
This wild deformity is very rare; only a few two-headed sharks have ever been recorded. And only six have ever been mentioned in published scientific reports. This tiny shark fetus is the first record of the deformity occurring in a bull shark.
The fetus has two heads due to a deformity called “axial bifurcation.” During axial bifurcation, a fetus begins to split to form identical twins. But sometimes, as was the case for this bull shark fetus, the division ceases before the fetus becomes two, and continues to develop only partially split. Axial bifurcation occurs in many different types of animals, including humans.
Had the mother shark not been caught, would the two-headed shark fetus have been born, maybe even itself reproducing and perhaps passing on its remarkable two-headedness to future generations? It’s highly doubtful.
According to Michael Wagner, co-author of the study, the shark probably wouldn’t have survived very long in the wild, even if it was able to be born.
“When you’re a predator that needs to move fast to catch other fast-moving fish ... that’d be nearly impossible with this mutation,” the Michigan State assistant professor of fisheries and wildlife told Live Science.
There’s another reason the shark (sharks?) probably wouldn’t have lived for very long (or at all)" Its body was tiny. Like, comically tiny.
“It had very developed heads, but a very stunted body,” said Wagner. Growing in utero is an energy-intensive endeavor, and developing two heads takes up even more energy.
The study was published in the Journal of Fish Biology.