• Rare shark has even rarer two-headed offspring

    By: Natalie Dreier , Cox Media Group National Content Desk


    A sawtail catshark in the Mediterranean is making headlines in the science world. 

    Scientists from Spain say they've discovered the first case of a two-headed shark developing in an egg-laying shark species, National Geographic reported.

    The creature was featured in an article in the Journal of Fish Biology.

    The shark species lives only in one region: the western Mediterranean, and is considered "near threatened."

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    Scientists were collecting embryos of nearly 800 sharks to study their cardiovascular systems. Only one embryo showed two heads.

    The embryo has two heads, two mouths, two sets of eyes, two brains, two sets of gills, two stomachs and two livers, but only one, shared, intestine.





    The condition, called dicephaly, is rare in the animal kingdom, but can be found in species from snakes to dolphins and even people.

    Normally dicephaly has been found in sharks that bear live young or lay eggs that hatch inside the mother.

    "There's a reason you don't see a lot of sharks with two heads swimming around: They stand out like a sore thumb, so they get eaten," George Burgess, director the Florida program for shark research at the Florida Museum of Natural History.

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