No One Knows Why Two-Headed Sharks Seem To Be Turning Up Everywhere

As if sharks with just one head weren’t scary enough, it now seems that seafarers have to contend with a rising population of two-headed sharks in the waters, yet the reason for their recent proliferation remains unclear.

Just last week National Geographic published an article assuring people that two-headed sharks aren’t a hoax or sideshow creation. They’re real, and they’re becoming more and more common, both hatching from eggs and from live birth, according to the Journal of Fish Biology. Recently, a fisherman in Florida caught a bullshark carrying a two-headed fetus and several years ago, a two-headed blue shark was found in the Indian Ocean.

Christopher Johnson

Most of the specimens discovered were embryos or infants, as the hardships associated with the two-headed mutation keep the odds of survival to adulthood very low. So while that is good news for the legions of divers and surfers out there, it doesn’t bode quite so well for the sharks that share the ocean with them.

The blue shark has produced the most two-headed specimens, but it’s unknown if that’s due to a systematic cause or just that they produce a tremendous number of offspring overall (up to 50 at a time).

A couple of prevailing explanations are guiding the discussion – either from inbreeding caused by low populations due to overfishing or pollutants and toxins in the water leading to mutations. While these are somewhat distinct issues, the common thread between them is human disruption of the sharks’ environment.

Either way, the issue is much more likely a symptom of a bigger problem than a crisis in and of itself. If it takes the shocking image of a two-headed shark to get people discussing measures to preserve aquatic environments, this strange development might just serve as a catalyst for change.

Or, conversely, it could just lead to more tweets like this: