Scientists confirm first two-headed bull shark. (Credit: Courtesy of Patrick Rice, Shark Defense/Florida Keys Community College.) Enlarge

Mar. 25, 2013 — Scientists have confirmed the discovery of the first-ever, two-headed bull shark.The study, led by Michigan State University and appearing in the Journal of Fish Biology, confirmed the specimen, found in the Gulf of Mexico April 7, 2011, was a single shark with two heads, rather than conjoined twins.

There have been other species of sharks, such as blue sharks and tope sharks, born with two heads. This is the first record of dicephalia in a bull shark, said Michael Wagner, MSU assistant professor of fisheries and wildlife, who confirmed the discovery with colleagues at the Florida Keys Community College.

"This is certainly one of those interesting and rarely detected phenomena," 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."

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. The two-headed shark died shortly thereafter and had little, if any, chance to survive in the wild, Wagner added.

"You'll see many more cases of two-headed lizards and snakes," he said. "That's because those organisms are often bred in captivity, and the breeders are more likely to observe the anomalies."

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