Two-Headed Shark Found by Fisherman

This two-headed bull shark fetus was recently found by a fisherman and described in a science journal. Photo: Reprinted with permission from C. M. Wagner et al

We’ve written about a cyclops sharkfreshwater sharks, and whorl-toothed sharks, but we have to add a new curiosity to the digital curio: a two-headed shark.

A fisherman working off the Florida Keys recently caught a bull shark, then opened it up to find that it contained two live fetuses, including one highly unusual one with two heads. The fishermen gave it to scientists, who wrote about it in an article published in the Journal of Fish Biology this week.

The scientists, led by C. Michael Wagner of Michigan State University, said it was the first known case of the phenomenon in bull sharks, and one of only about a half dozen recorded cases of a two-headed shark anywhere.

“In and of itself, this single natural history observation does not tells us anything Earth-shattering about the health of the world’s oceans or populations of bull sharks,” Wagner told Ocean Views via e-mail today.

“It’s simply a rarely observed phenomena that we recorded. Yet, it does capture public attention, and what a great opportunity for journalists like yourself to shine the light on some interesting information that does bear on that very important question.” [Does the two-headed shark teach us anything about the health of the ocean?]

As further reading, Wagner pointed to the recent Ocean Health Index published in the journal Nature by Benjamin Halpern and colleagues (which we covered here).

Why Two Heads?

The two-headed bull shark displays a process technically called “axial bifurcation,” in which the embryo doesn’t finish splitting into two separate individuals (twins). This mutation has been seen in other animals, including humans.

According to Wagner’s team, such individuals rarely survive in the wild, since they are at a big disadvantage when it comes to finding food and avoiding predators. In this case, the two-headed bull shark also ended up with a very small body, since so much energy went into growing two heads.

Wagner said the fishermen who found the animal told him it died shortly after being removed from its mother. “It likely would not have survived very long had it been born naturally,” said Wagner.

Studying such rare organisms may help us better understand developmental processes, Wagner added.

Update: Wagner pointed out, in response to a reader question below about sharks not having bones: “It is true that shark skeletons are formed of cartilage, not bone. Shark cartilage is sufficiently dense to be imaged by x-ray. It is a commonly used technique for examining museum collection specimens that are rare, and when there is a desire to keep the specimen undamaged (e.g., see the Smithsonian Institution exhibit on fish diversity).”

Two-headed bull shark fetus x-ray
An x-ray of the fetus. Photo: Reprinted with permission from C. M. Wagner et al


Check out this bull shark video from National Geographic’s archives:

Brian Clark Howard covers the environment for National Geographic. He previously served as an editor for TheDailyGreen.com and E/The Environmental Magazine, and has written for Popular Science, TheAtlantic.com, FastCompany.com, PopularMechanics.com, Yahoo!, MSN, and elsewhere. He is the co-author of six books, including Geothermal HVACGreen LightingBuild Your Own Small Wind Power System, and Rock Your Ugly Christmas Sweater.

  • John

    Like a SYFY made for tv movie. LOL

  • Bob Forsberg

    Sharks abort physical imperfections so not as to damage the gene pool. Humans are the only species that prevents these actions while at the same time terminating perfectly healthy specimens.

  • Johnny

    F$&@ you, BP!! Look what you did!

  • SumGai

    This whole story is false on it’s face. Everyone knows sharks don’t have bones, so you can’t see them on an xray! #badPhotoshop

    • Those photos were published in a reputable science journal, and I emailed with the researcher to verify. I will ask him about your comment though, I did learn something similar in school. My guess is it’s a nuance…

  • jennifer

    I don’t know if I should be amazed or terrified !

  • Cleo

    This has nothing to do with Fukushima continuing to pour highly irradiated water into the ocean, right? because decades later, Chernobyl is PERFECTLY safe so two years later, Fukushima must be even safer.

  • Vikas

    seems more like birth time anomaly to me. It has happened in humans also when fetus combines and fuses to come our as single organism with two sets of features. I would not say this is a trend but it happens i do not think this would be repeated as gene mutation

  • cole

    Sharks do not have bones but they do have cartalage, that is what is showing up in the x-ray. Wow, do you really believe such a reputable company like National Geographic would really sacrifice their good name for a false claim.

  • Blayne

    I see Jesus.

  • Brandon

    Sharks have cartilage skeletons whis does not absorb the X-rays…X-rays like this one are performed by injecting a dye which DOES absorb said X-ray

  • Michael B


    You are correct in that sharks do not have bones, however they have dense cartilage that acts very similar to bones. This is likely what you are seeing in the x-ray. Have you ever seen/felt a shark jaw?

  • Justin

    Just because it appears you can “see bones” doesn’t mean that actual bones are there. It is just the denser material absorbing more x-rays than the other areas. Denser material does have to mean bone.

  • Justin

    Edit: It should read: “Denser material does NOT have to mean bone.”

  • carter

    @Sumgai, you can still see cartilage on x-rays.

  • Sharky

    SumGai: Sharks skulls, jaws, and spine are fortified with calcium salts, making them thicker and stronger and visible on x-ray.

  • Anonymousexpectus

    Dear Sumgai: Sharks do have cartilage which WILL show up on an xray. But you’d rather say the article is false than do a little bit of your own Google image search. Wow Amurka. Its called Critical Thinking. You should try it sometime.

  • The Shark With 2 Heads

    LOL cartilage will show up in an x-ray. Yes we sharks do not have bones, but hard cartilage is what you are seeing in my x-ray. THANKS

  • Ant

    Sharks dont have bones? wow that wins for the most wrong statment of the day…. what are they ? jellyfish with teeth

  • Sean

    @ sum gai. Sharks do not have bones but they do have cartilage. Since the two headed fetus was quickly preserved by the scientists who received it then it would make perfect sense that they could obtain an x ray image.

  • jm

    More than bone shows up on x rays. Cartilage is dense and shows up especially strong in cases like the vertebrae of the shark fetus. A google image search will turn up many credible shark x ray images.

  • Thascia Spindola

    SumGai, Since when are you a Radilologist? CT or MRI shows cartilage, it’s the publishers term (x-ray), not the scientist.

  • Nicolette S.

    i thought that sharks didnt have bones… although the pictures look very real i dont think this is a real finding. i believe you should investigate more before putting out accusations out on your website.i would hope this 2 headed shark creature is real not a false animal.

  • brosky

    Sharks have spines. The rest of their bones are cartilage.

  • zMoRfz

    HI there, Sharks do have skeletons but they are made of cartilage instead of bones. You can definitely see cartilage with X-Rays.

  • Joe

    Below why the jaws show as well as the spine.
    “Their skulls, jaws, and spine are fortified with calcium salts, making them much thicker and stronger.”


  • Nick

    you can see soft and hard tissues on X-ray with enhanced diffraction!

  • Joe

    @ Bob Fosberg
    Have you ever heard of a miscarrired pregnancy? The human body also has this capacity…
    Unfortunately the human mind, as you state, also.

  • robert epps

    ( Everyone knows sharks don’t have bones,….)
    true, they have skeletons made of cartilage (the teeth are bone though)

    ( so you can’t see them on an xray! ….)
    only technicly true, you can’t see bones(they dont have em), but you can see material density, and cartilage is more dense and blocks radiation better than the soft tissue and will show up on xray.
    the reason bones show up on xrays is because they are more dense than most other tissues

    given the amount of detail and backstory to go with it. as well as a physical proof.

  • Eric Johnson

    This is actually the clone of a politician, which one is anybody’s guess.

  • MDog

    SumGui’s comment incorrect. I am an engineer working in the CT and medical imaging field. Soft tissues can be imaged using Xray. Bone will show up better because it has a hire density but that does not mean you cant image soft tissues.

  • Krissy

    Actually, sharks do have bones. Their teeth. They do however also have something called cartilage. Which is like abone but softer and decomposes. Which means is is signifficantly less likely to turn into a fossile. And why there is no fossile records for sharks, which is why people know that “shakrs don’t have bones.”

  • Joseph slocum

    I have a similar speciman.I have a 2 headed spiney dogfish fetus that I removed from a pregnant shark caught on a boat here in New Jersey.I have good pics of it.If anyone would like to see it email me and I could send one to you.

  • Joe

    Correction: Sharks do have bones, but they do not show up on an X-wray due to differaction. Go back to sience school NG!!! LOL

  • name

    i think this article was all right

  • ma’

    Hey! I see an image of someone praying in the MRI. Funny it should appear at Easter!! Praise be to God!

  • Jack

    I’m just thinking, how old is the fetus? Did it stop deleveping inside the adult shark and ready to be born?

  • Nicky

    Seriously people?! I don’t know much about science, but how can anyone still say the same thing in every single comment? Sharks have very dense cartilage which explains why it shows on the x-rays. It’s really not that hard to understand.

  • Rick

    Bones no bones….. make no bones about it I believe this is due to all the Corexit BP dumped in the Gulf. ( witch is still spewing oil) There have been a huge increase in deformities in most animals there and up the coast. Look up crabs without shells, shrimp without eyes ect. Next time you see how wonderful the Gulf is due to BP’s actions think twice. Notice how none of the state reps don’t ever eat any of the food. But tell you come on down and enjoy.

  • az

    Would have hit a lamp post head on.

  • Ms. Billie M. Spaight

    Fascinating. My first thought was “wow, a Siamese-twin shark.” Poor little fellows. As a one-off (or should I say two-off) it is not alarming. However, if more of these cases appear, then we really need to find out why.

  • philip

    Why was this man fishing for sharks anyway? they are threatenend as it is….with far too many being caught just for their fins

  • Judy

    My first thought when seeing this story on TV news was the BP oil spill and corexit used in the Gulf. We don’t know how many of these deformities are natural or human-caused.

  • chanmac

    Sooo 1. How and why is he fishing for sharks… I thought that was not legal? 2. At the least mothers (obviously this one was pregnant) should not… The dude just tech killed 4 or 5 sharks at once….

  • Kath

    Really?? Sharks are in a lot of trouble and we still allow people to kill them and then glorify the killing….shame on all involved!

  • Nadia

    I’m surprised that neither the National Geographics, nor any of the scientists mentioned in this article say anything about the impossibility of this two-headed shark to be born in the first place, let alone be born but not survive long!!! I thought shark embryos are very competitive in the womb and that ultimately the strongest one will eat the other siblings – while still in the womb – and be the only one born! So, this two headed shark could not have been born. Which leads me to suspect that such oddities may occur more frequently (more than once or 6 times), but that they simply get naturally eliminated and never be born or seen in the waters! Darwinism at its best?

  • Faith

    So glad to know this idiot killed a pregnant shark – bad enough sharks are endangered and villified – now the mother, the other baby, and the 2 headed fetus all died terrible deaths. For what??

  • Alex

    What the heck! I mean this is cool and all, but shark fishing and then he cut open a pregnant mother!?!?! Ugh… I can never understand human beings.

  • Randy

    Let me get this straight. He caught a shark, killed it and all it’s offspring. And sharks are threatened already.
    Great story NatGeo.

    • Randy, I take your point, although I’d add that we had nothing to do with originating this story. The research about the two-headed shark fetus was published in a reputable science journal, which is fair game for public discourse. I interviewed the lead scientist of that paper for my post, which I feel is newsworthy.

  • Phillip

    More evidence of global warming, oops, I mean climate change.

  • Andrew

    How can NGS so blithely report the killing of sharks like this. The Society often laments the numbers of sharks being killed every year (100 million apparently) then features a story like this with no condemnation of the killing of this shark and it’s pups at all.

    • Hi. Point taken, we are certainly very sympathetic to the plight of sharks here, and in fact the Society sponsors a number of researchers looking into shark conservation. By linking to the Ocean Health Index I had hoped that the conservation message was getting across, and I had asked the researcher about what it might mean for the health of the ocean.

  • Charlie

    In the name of science and research, everything is possible.

  • loretta

    It is so sad that people still fish and kill other living creatures, especially one that is not of harm to people, far more sharks are killed by humans than humans are ever killed by sharks. Stop fishing it is cruel!!!!!!

  • Wade-Ryan

    I would hate to be on the NatGeo comment response staff having to constantly appease so many of you crusaders out there worrying about a leagally caught shark.
    First of all read all of the words, not just the ones that tickle your nether regions, “fisherman” & “working” these are critical to the entire article. Now when I read those 2 words its not difficult to understand why the shark was “opened up.”
    How about giving the hard working man some credit; he gave it to scientist to study, he didn’t throw it in the chum bucket, he didn’t sell it to a sushi restaurant to put on display, he gave it to science. The science by the way that keeps this website and magazine in business and the poor guy responding to your sycophantic cries employed.
    So before putting your whining and complaining before the poor defenseless sharks and before the guy out making a living so his family doesn’t become extinct, read the friggen article.

  • Davin

    Hmmm,mmm, sure could go for some nice , savoury, shark-fin soup!

  • Spencer

    Can anyone tell me if this is maybe a product of the on going
    Fucushima radioactive water constantly circulating around the globe ,probably being dumped into the pacific this very moment
    By our friends at tepco?

  • Tony D

    Regarding Eric Johnson’s comment about a this being a clone of a politician. I believe it’s the next step in the evolution of politicians solving the problem of speaking out of both sides of their mouths. Two faces and two mouths right from birth.

  • Gail

    Reading many of the above comments shows how many people out there have minimal spelling skills. Did none of you go to elementary school? Or did you spend your time chatting instead of learning????

  • bret

    Humans kill their unborn babies by the millions but avoid displaying the fetuses for science. Why be surprised by this story? I do appreciate the effort made by the fisherman to make this available to NG . And the comment comparing this to a politician – now that’s good.

  • Bill

    All you baby killing (pro-abortionists) liberals whine about a fisherman working. Then run around eating sushi and getting pregnant then killing that baby. Hypocrites!!! I thought it was a fascinating article. Yes I am a hunter too, love venison

  • Julia

    Loretta, I think it is fine to fish- no different from eating a cow as a hamburger or a chicken as chicken nuggets. These are very docile animals most of the time and we “cruel humans” are killing them for food. Plus. if YOU don’t like it, YOU don’t have to eat or support it.

  • lex

    Demand civil righs for two headed sharks.

  • Emily

    I think that maybe National Geographic should do a article on Common Misconceptions About Sharks to clear up all of this nonsense about whether a shark is all bone are not and save everyone the grief.

  • Olivia

    So there were also a couple other sightings of two headed sharks? What kind of shark?

  • Eric V. Johnson

    I Feel Were Going to See MORE of These Mutations AND In Other Genus n Species Also, Bcuz of All the Ferterlizers Nitrates ( NO2 ) Compounds That IS Being Flush into OUR Oceans Every Second…just sayin…Iam Surprise WE Havn’t Seen This Already Long Long Ago.

  • Lily

    That is flipping cool but please don’t kill it put it in an tank or something it is cute

  • rakesh bisne

    its ammazine

  • Mitch

    How would the mother have delivered such a baby? I wonder if she would have resorbed the fetus, or if she might have died when unable to pass the baby through the birth canal.

  • Joy

    How did a news story about an epic two headed shark turn into a crusade against killing innocent fish? My best buddy the grizzly bear would heartily disagree. As does my stomach. Nom nom nom fish.

  • Debbie Brown

    But it’s a DEAD two headed shark now – thanks to an idiot one headed ape !!!!!!

  • Vedran

    Looks like Simpsons episode IRL. LOL

  • Chris Johnston

    i have also caught a two headed shark , it was a blue shark that i caught in the indian ocean around 3 years ago

  • Chris Johnston

    The shark stayed alive in a tank for several hours but sadly died,

  • Ryan

    Ust have been swimming next to Fukashima.

  • Captain Dave

    Im a charter captain in the Keys and I’ve never killed a shark. i’ve seen a huge decrease in shark sightings in the last 20 years. Shame on him for killing a beautiful apex predator which has NO FOOD VALUE. Leave your ego at home. Catch and kill what you can eat and catch, take a photo and release the rest. People who kill for the sake of killing or to show off make me sick. All sharks should be protected as every study shows that they are being destroyed faster than they can recover.

  • The Wiz

    Only someone misinformed would worry about this shark being harmed. In the animal world most abnormalities like this die shortly after or during birth if not sooner. For the purity of the species they are destined to die naturally. If not this shark would be eaten by another animal any way. It’s called “The food Chain” not birth of a new species. Even if this shark somehow survived it would not reproduce. You bunny huggers need to get real.

  • Mohini

    Have you heard of a 2 headed cobra? Some one spotted the snake in cantonment, Bangalore India.A picture of it was E mailed to me last yr. It was in a temple. Amazing.Can you explain.unlike the shark, the snake with 2 heads has survived.

  • Umer

    Oh!!!!!!!!!!!!!!!!!! Thats Amaizing…………………. Subhan Allah

  • Ferretylove

    Well said, Captain Dave!! I can’t stand killing for sport! It ‘feels in my heart’ just as wrong as any other pre-meditated murder!

  • terry

    I have to agree with Gail from Edmonton. I am also amazed
    at the lack of grammar and spelling of so many readers of NG!
    Does this reflect the lack of interest and basic knowledge of
    Life and changes to our world as well? I suppose we all should climb in our little boxes, close our eyes, hold our breath and practise counting backwards. TY NG for all you do and share.

  • jesse

    i think that eating meat is wrong. I was a sniper in the US Army for 10 years. I have more respect for cows than i do humans. Killing a innocent animal to fufill our gluttonous ways is just wrong in many different ways. Also killing an helpless creature of the world makes you a man wow you are so wrong and you have the biggest little mans complex i have ever seen.


    it is terrible news. this kind of mutation is mainly due to pollution of ocean with gas spilled to ocean and nuclear wastes. i will not eat sea food anymore.

  • Silwni

    I am more concerned that a fisherman murdered a pregnant shark and then killed it’s young too. Maybe the same should happen to him.

  • A Essak

    Subhan allah.
    These are the signs and lessons have to be learnt. There are more signs out there.
    Look out !!!
    We must look were we went wrong?
    God is Great.

  • Gregory B Williams

    Sharks are over harvested around the world. I agree with the vegans and vegetarians and strongly disagree with anti-bunny hugger (I guess he means those of us who care about the environment). It’s not a sign from God, or necessarily a sign that the shark has been affected by our polluted oceans, just a freak of nature that is interesting to see.

  • Dylan

    I am a huge advocator of protection of the species, however there are quite a few misconceptions that i am seeing in these comments:
    1. I love sharks and greatly advocate the protection of them, but Bull Sharks are nasty creatures. They are essentially every shark-bite story you have ever heard in your life, hince why the fisherman had killed it. (Not to mention that the fetus would have died at birth with sucha deformation)
    2. This isn’t an effect of pollution, no radioactive chemicals, no outside force has affected how it was created. The fetus is a shark with a disability much to the same way that a four-legged kid is born.
    3. Finally, this isn’t the reporter’s fault, he was reporting on an interesting story

  • Al M.

    I wouldve sold it to Mike & Evan and that weird guy that glues the bones together at Obscura in NYC.

  • Ren

    We do live in a polluted world where chemicals do find access into water systems, no matter how much care is taken to ensure that this doesn’t happen.so why should it not happen with fish in the ocean ?

    Many years ago I was fishing in an outback river and all these gorgeous little fish that were caught had 2 tails and extra fins…I was disgusted and threw them back in but we’ve caught yabbies with extra claws and tails too, so I would imagine that abnormalities like this happen more often than we ever hear about them.. so although mutations may happen in nature , they are rare and possibly had this fisherman not caught the shark we’d never have known ..
    This is just my opinion….

  • FrogGod1

    so its not just a bad movie- 2 Headed Shark attack (http://en.wikipedia.org/wiki/2-Headed_Shark_Attack)
    perhapps God was inspired by the movie

  • alex the tortle

    well even though im a tortle i feel bad for this little shark.

  • Annarexxette

    For those of us who haven’t ever looked in a Zoobook, Sharks do have bones, but not many. They have a spinal column, with vertebrata, a primitive sort of skull, and a primitively hinged jawbone. The rest of their comparative “skeletal structure” is actually made of cartilage, the same stuff the upper part of your ear is made out of. The article actually states that shark’s cartilage is dense enough for X-rays to show, as cartilage is a very strong, thick tissue.

  • Selvamoorthy

    Though we cross such creatures then and therein our life, it is true that few second glimpses on those make surprise while seeing in person and confusion if it is seen in print

  • Vicki

    when did this event take place im doing a report on it and i need the info ASAP thanks for your time

  • Evan

    to loreeta.
    Humans didn’t climb to the top of the food chain to eat tofu.
    i don’t know about in new zealand, but here in texas we understand that if your an apex predator that means you eat meat. and that in cludes fish. if the person mentioned in this article was legaly fishing and caught the shark then by all rights he is allowed to do with it as he will.
    personaly you sound like a member of PETA. don’t you understand that is one of the worst insults i can bring down on your head? hypocrite!

  • Trevor


  • Heather

    I too and concerned that this fisherman slaughtered a pregnant bull shark, I acknowledge that these creatures are involved in the majority of shark bites however that is no reason to cleanse the sea of them altogether, it is disturbing to think that people consider the role of the so called ‘apex predator’ to wipe out or dominate over all other creatures. Surely a balance is key for us all to survive? This type of wreckless behaviour eliminated a number of sharks in our oceans that day.

  • Emily

    Why would this fisherman go and slaughter the shark in the first place? Did he have any specific reason to? NO. He killed an innocent healthy animal. People should be reprimanded if caught doing this.

  • John mc. troolson

    cool shark but please don’t experiment on it

  • Poyney

    I do wonder if the sharks are as opinionated?!?? I wonder if one of the ‘omg a man killed an animal’ would not be eaten by a shark?! It’s an interesting article, and no difffernt to Siamese twin so I do not believe in my miss informed (like most I have noted on here) opinion that it has any kind of freaky messed up radioactive reaction!!! Also the reporter is reporting an article of interest thus if you comment on this you are SUPPORTING the interest raised in the article and this type of storey!! Save the Mosquitos…. Save the flys…. Save the bugs…. Save a cow and eat a vegetarian?!?!!!!! Now let’s penalise the worlds food chain….. Damn those lions, damn those penguins (they eat fish) ….. How about we digest the beauty of this creation that would not have been seen if the fisherman hadn’t found the mother shark?!?! Would have died and never have been known of now THAT would be a waste!!!!

  • i want to adopt a dog

    Do by yourself understand how numerous pets are starving even if another person acquire cares of them/ if oneself seriously care for them, why don’t your self ship some foods to http://www.animals-sanctuary.com/ ?

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