Last week my buddy Brian over at National Geographic turned up a wonderfully bizarre picture of a two-headed blue shark fetus. Check out these photos:

Two-headed baby shark

Photos courtesy of Christopher Johnson/National Geographic

The crazy thing is that's not the only double-headed shark that Brian has come across. Last month he wrote about a two-headed bull shark and just a few weeks ago he penned a round-up of some other two-headed animals.

Brian's latest find was found by commercial fisherman Christopher Johnson (one of Brian's readers) back in 2008 off the coast of Western Australia. Johnson cut the two-headed baby shark out of a pregnant blue shark that he and his fellow fishermen pulled out of the sea. They're required to cut open pregnant sharks because fetal sharks count against the quota of sharks that they are allowed to have on board.

It's not clear what caused this biological abnormality, but it's likely to have been a result of some mixed-up genetic baking. The most famous pair of cojoined human twins, Chang and Eng Bunker, toured with P.T. Barnum's circus back in the 1800s and coined the term "Siamese Twins" (the Chang brothers were born in Thailand, which used to be known as Siam).

Here are a couple more shots of the two-headed baby blue shark, all by Christopher Johnson.

Two-headed baby blue shark

Two-headed baby blue shark

If you'd like to read more about sharks, check out these articles here on MNN:

Are you on TwitterFollow me (@sheagunther) there, I give good tweets. And if you really like my writing, you can join my Facebook page and visit my homepage.

All photos reprinted with permission.

Shea Gunther is a podcaster, writer, and entrepreneur living in Portland, Maine. He hosts the popular podcast "Marijuana Today Daily" and was a founder of Renewable Choice Energy, the country's leading provider of wind credits and Green Options. He plays a lot of ultimate frisbee and loves bad jokes.

Two-headed baby blue shark pulled from Indian Ocean
Most of the time, nature is pretty good at following the "one baby, one head" rule. But every now and then, something goes wrong and you get this.