Just when you thought it was safe to get in the water... Jaws Two! Fisherman discovers first ever two-headed bull shark

Shark - with two heads, hearts and stomachs - found in Gulf of Mexico
Discovered by a fisherman when he opened the uterus of an adult shark

PUBLISHED: 07:27 EST, 26 March 2013 | UPDATED: 14:02 EST, 26 March 2013

American scientists have confirmed the discovery of a two-headed bull shark foetus - believed to be the world's first ever.

The single shark - with two heads - was found in the Gulf of Mexico, according to a study by Michigan State University and reported in the Journal of Fish Biology.

It was discovered by a fisherman when he opened the uterus of an adult shark in 2011, around a year after the Deepwater horizon oil spill, in the Gulf of Mexico.

The single shark, with two heads, was found in the Gulf of Mexico, by a fisherman when he opened the uterus of an adult shark

While other species of sharks have been born with two heads - including blue sharks and tope sharks - this is the first record of it in a bull shark.

Bull sharks are one of only a few species of shark that attacks humans, and are also popular with fisherman, as they put up a 'good fight'.

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Michael Wagner, MSU assistant professor of fisheries and wildlife, told the Register: 'They're hardy little critters.

'But despite this, the two-headed specimen probably would have died after birth. It was near-to-term, but should have been a lot larger – the body looks to have invested so much energy in growing a separate head that the rest of the body was foreshortened.'

MRI scans of the shark revealed two distinct heads, hearts and stomachs. The rest of the body then rejoined to form a single tail

BICEPHALY - WHERE TWO HEADS ARE NOT BETTER THAN ONE

The condition of having more than one head is known as polycephaly, with two-headedness described specifically by the terms bicephaly or dicephaly.

But the creatures rarely live beyond a few months.

Each head of a polycephalic animal has its own brain, and they share control of the organs and limbs, though the specific structure of the connections varies.

Such animals often move in a disoriented and dizzy fashion, with the brains 'arguing' with each other leading some specimens to simply zig-zag without getting anywhere.

In snakes, each head may attack and even attempt to swallow the other.

Most of the two-headed creatures shortly after birth, and in this case the creature died shortly after it was discovered,

Mr Wagner said there were many more cases of two-headed lizards and snakes, because they are often bred in captivity where breeders can observe and monitor the oddities.

After it was discovered, the shark was taken to the marine science department at Florida Keys Community College and then to Michigan State’s campu where Mr Wagner and his team used magnetic resonance imagining (MRI) to study it.

They revealed two distinct heads, hearts and stomachs.

The rest of the body then rejoined to form a single tail.

While the professor noted in his research that some may link the deformed shark to exposure to pollutants, to link it to the Deepwater Horizon oil spill would be 'unwarranted'.

He added: 'We simply have no evidence to support that cause or any other.'

According to the International Shark Attack File, there were 80 instances of unprovoked shark attack against humans in 2012, with seven deaths.