25 March 2013
Two-headed bull shark discovered
by Will Parker
Marine researchers at Michigan State University have confirmed that the first-ever, two-headed bull shark to be discovered is a single shark with two heads, rather than conjoined twins.
According to researcher Michael Wagner, the specimen, found in the Gulf of Mexico in 2011, represents the first recorded instance of dicephalia in a bull shark. "This is certainly one of those interesting and rarely detected phenomena," he 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."
The difficulty of finding such oddities is due, in part, to creatures with abnormalities dying shortly after birth. In this instance, a fisherman found the two-headed shark when he opened the uterus of an adult shark. "You'll see many more cases of two-headed lizards and snakes," Wagner suggests. "That's because those organisms are often bred in captivity, and the breeders are more likely to observe the anomalies."
Wagner was able to detail the discovery with magnetic resonance imaging. Without damaging the unique specimen, the MRIs revealed two distinct heads, hearts and stomachs with the remainder of the body joining together in back half of the animal to form a single tail.
Wagner notes that some may want to attribute the deformed shark to exposure to pollutants. "Given the timing of the shark's discovery with the Deepwater Horizon oil spill, I could see how some people may want to jump to conclusions," he said. "Making that leap is unwarranted. We simply have no evidence to support that cause or any other."
Source: Michigan State University