It may sound like sci-fi, but two-headed sharks are real, and scientists say they're now popping up all over the world. National Geographic reports that sightings of two-headed sharks are still pretty rare overall, but the new sightings are giving scientists more opportunities to study this freaky mutation in these beasts of the sea.
According to National Geographic, fishermen in Florida caught a female bullshark that had a two-headed fetus in its uterus, and then in 2008, a fisherman in the Indian Ocean came across a blue shark with two heads.
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Now, the Journal of Fish Biology has published a report out of Spain that is the first of its kind to describe a two-headed shork born of a shark who lays eggs, rather than live offspring: the Atlantic sawtail catshark. In the report published in early October by Spanish scientists, the authors describe the embryo as having a single body with two heads, and each had two eyes and a mouth and a brain. The embyo's body had four anticipated dorsal fins, and two anterior and posterior fins on the right and left side.
As far as guts go, the embryo had two hearts, two stomachs, two esophagi, and two livers. The report's authors wrote that the mutation is most likely caused by pollution or viral infections in the sharks.
