What’s scarier than a shark with one big head? How about a shark with TWO big heads? What’s scarier than that? How about a shark with two big heads in a lab that “claims” it “found” the two-headed embryo while doing a “study” on cardiovascular systems? If this all sounds fishy in a two-headed way, there’s more.

According to their report in the latest issue of the Journal of Fish Biology, biologists at the University of Málaga in Spain say they were sifting through hundreds of Atlantic sawtail catshark (Galeus atlanticus) embryos as part of their research on how their cardiovascular system develops when they saw a two-headed embryo growing inside a translucent shark egg case. If you’re prone to nightmares, you may want to skip their description of it.

Each head had a mouth, two eyes, a brain, a notochord [like a spinal cord] and five gill openings on each side. [Inside the body] were two hearts, two oesophaguses, two stomachs, two livers.


Big deal, you might think. We’ve seen two-headed fish, lizards and mammals before … even two-headed sharks. True, but this is the first known two-headed conjoined twin ever recorded coming from an egg-laying shark. About 40% of the 400 or so species of sharks lay eggs (bamboo sharks, wobbegong sharks, swell sharks and catsharks are examples) while the rest give birth to live young. Two-headed sharks are also very rare among live birthers. Those found in the wild have been young or fetuses so their survival chances are probably slim.

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A two-headed survivor

This two-headed shark was found (suspiciously) in a laboratory. Researcher Michelle Heupel claimed the team at the lab had nothing to do with it – it was genetics. Florida Museum of Natural History director George Burgess agrees.

We see two-headed sharks occasionally. It's an anomaly, caused by a genetic misfire. There are lots of different kinds of genetic misfires, and most don't make it out of the womb.

Well, this one did. The study says the team euthanized the embryo in formaldehyde and alcohol to preserve it for further study.

Will they study it to learn how to prevent dicephaly (two-headedness) or to create a species of killer two-headed sharks to help Spain once again rule the oceans?

Paul Seaburn

Paul Seaburn is the editor at Mysterious Universe and its most prolific writer. He’s written for TV shows such as "The Tonight Show", "Politically Incorrect" and an award-winning children’s program. He's been published in “The New York Times" and "Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. His “What in the World!” podcast is a fun look at the latest weird and paranormal news, strange sports stories and odd trivia. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn't always have to be serious.

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