Mysterious two-headed sharks are all over the place, and scientists are baffled.
Turns out two-headed sharks are more common than most people realize.
Nat. Geo recently brought the issue back to the spotlight. In the last 10 years, two-headed sharks have appeared more frequently all over the globe. The strange occurrence has been observed in multiple shark species, including bull sharks, blue sharks, and sawtail catsharks.
A few years back, fishermen in Florida reeled in a pregnant bull shark that was carrying a two-headed fetus. Then, National Geographic reader and professional fisherman Christopher Johnston sent the journal some images of a two-headed shark pup he had found and photographed in the Indian Ocean.
Christopher didn't think too much of it at the time, as the pup died soon after he found it. But now, things are getting even stranger.
It seems a team of Spanish researchers found an embryo of an Atlantic saw tail catshark that has two heads. The report of the incident came out of a study published in the Journal of Fish Biology.
While the team was raising sharks for lab research, they located the embryo in a translucent shark egg! How cool is that?
To make this whole phenomenon even more interesting, this was the first documented case of this happening in a oviparous shark species, or a shark that lays eggs. The team leader stated that he is not sure if the animal would have survived once hatched. The team seems to think that two-headed offspring do not live long enough for people to find them.
So, what is causing this to happen?
Well, that's up in the air at the moment. The incident with the Spanish research team is interesting because it took place in a controlled environment. This suggests that in that case, it was most likely a genetic mutation.
"I would like to study these things, but it's not like you throw out a net and you catch two-headed sharks every so often," marine scientist Nicholas Ehemann stated. "It's random."
In other instances that have taken place in the wild, it could be the result of infections, chemical imbalances, radiation, pollution, or just a dwindling gene pool due to overfishing.
Unfortunately, for now, the two-headed shark phenomenon is going to remain a mystery.