The above specimen was found in an adult bull shark by fishermen in the Gulf of Mexico on April 7, 2011. According to Michigan State University researchers, this is the first recorded instance of a two-headed bull shark, although two-headed specimens of other sharks have been found in the past. Due to its deformity, it would not have lasted long in the wild.
According to the UPI:
“This is certainly one of those interesting and rarely detected phenomena,” MSU fisheries and wildlife Professor Michael Wagner said. “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.”