Two-headed bull shark found off coast of Florida

Marine scientists have confirmed the discovery of a two-headed bull shark, caught by fishermen working off the Florida Keys on 7 April, 2011.

It's the first two-headed version of the species to have been found in the wild, with specimens usually dying shortly after birth. This cute little fella was found alive in the uterus of an adult bull shark as it was cut open by the fishermen, though, sadly, it died shortly afterwards.

Marine scientists at Michigan State University confirmed the discovery, with a study published in the latest edition of the Journal of Fish Biology. Using magnetic resonance imagery, the scientists discovered that the shark had two distinct heads, hearts and stomachs, with the rest of the shark merged together with the organs shared.

The shark had little chance of surviving after birth regardless of its mother being caught, according to Michael Wagner. He said: "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."

Two-headed sharks are not hugely common, though previous specimens identified include a two-headed top shark from 1934 and a two-headed blue shark found two years ago. It could be caused by a genetic mutation, or by environmental factors -- though Wagner is keen to rule out blaming the BP Deepwater Horizon oil spill, saying "we simply have no evidence to support that cause or any other".

He said: "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."