The animal is a single shark with two heads, not conjoined twins
This March 25, the Journal of Fish Biology witnessed the publication of a study documenting the discovery of the first-ever two-headed bull shark. The scientists who got the chance to analyze the animal's anatomy wish to stress the fact that, rather than being conjoined twins, this shark is a two-headed specimen.The shark was discovered by a fisherman in the Gulf of Mexico in April 2011. As the fisherman later told scientists, this peculiar shark was still a fetus when he stumbled upon it. Thus, the two-headed bull shark was found inside the uterus of an adult specimen.
Due to its peculiar anatomy, it is unlikely that this bull shark would have managed to survive in the wild after having been born.
In fact, this is precisely why such odd specimens are extremely difficult to come by: they die of natural causes long before the scientific community becomes aware of their existence.
“You’ll see many more cases of two-headed lizards and snakes. That’s because those organisms are often bred in captivity, and the breeders are more likely to observe the anomalies,” researcher Michael Wagner explains.
Besides having two heads, this shark was found to have two hearts and two stomachs. Still, as observable in the picture next to this article, the rest of its body formed just one tail.
“External examination, radiography and magnetic resonance imaging revealed a case of monosomic dicephalia where the axial skeleton and internal organs were found to divide into parallel systems anterior to the pectoral girdle resulting in two well-developed heads,” the researchers write in their paper.
According to the official website for the Michigan State University, two-headed sharks have been documented before in species such as blue sharks and tope sharks.
However, this was the first time when a two-headed bull shark was discovered and studied.
As Michael Wagner puts it, “This is certainly one of those interesting and rarely detected phenomena. It’s good that we have this documented as part of the world’s natural history, but we’d certainly have to find many more before we could draw any conclusions about what caused this.”
Despite the fact that the shark was found at the site of the Deepwater Horizon spill, the scientists maintain that there is no evidence to link its peculiar anatomy to environmental pollution.