Can coral polyps grow in my skin?

No matter how carefully you may dive in saltwater, if you do it long and often enough you’ll likely have an eventual run in with a coral (or hydroid, sponge or similar cnidarian) that can inflict a painful envenomation. Sometimes these wounds can be long-lasting, as in 3-4 weeks or more, before significantly improving. Also, they may seem to be getting better or even almost entirely resolve, only to return.

This has led one diver to ask me, “Can coral polyps grow in my skin?” The short answer is, “No, it is not physiologically possible for coral, hydroid or sponge cells to live on or within the human body.”

In general, corals, sponges and the like need a number of conditions to grow and survive. These include constant bathing in water within a range of salinity/pH and an adequate supply of algae/zooplankton and dissolved nutrients’ Some require a host bacteria (zooxanthella) to assist in nourishment, and calcium carbonate saturation to allow for the formation of their colonial body structure. Many also need sunlight. This constellation of requirements is extremely unlikely to exist on or within the body.

However, it is possible for fragments of coral to become lodged beneath the dermis and for the body to mount a prolonged allergic reaction to them with subsequent sloughing of affected skin. In some cases, debridement or even surgical removal is required to resolve the reaction. It is also possible for coral scrapes/punctures to become infected, a situation that also requires treatment. This needs to be carefully monitored.

An individual with a diving-related skin wound that does not appear to be resolving, or is getting worse, should consult a dermatologist. An x-ray may be useful in imaging coral fragments large enough to require removal and topical/systemic antibiotics may be useful in resolving infection.

Doc Vikingo
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14 thoughts on “Can coral polyps grow in my skin?”

  1. My parents dove frequently in Bermuda in the 60’s – teaching diving on weekends. On one occasion, my mom had a cut on her leg (shortie wetsuit) and they dove when the coral was spawning. Later she complained of pain in that area. My dad thought the timing could mean that coral was growing – but the doctors thought he was crazy. He dug it out of her leg himself 2 mths later – it was coral.

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  2. For what it’s worth, I experienced a slight graze, on my foot, from coral, in the tuamoutoos. The graze partially healed, but became infected on and off over about 4 weeks. After the infection worsened, whilst in Bora Bora, I visited a doctor who gave me an appropriate antibiotic. The infection quickly disappeared completely, but months later a lump appeared in the approximate location of the initial coral graze. Over the following months the lump grew. Approximately 6 months after the initial graze I cut the small lump open. The content was small grains, approximately 1mm in diameter, of a hard white substance, which penetrated to about 1cm under the skin.
    I didn’t consult a doctor, but the only explanation I can come up with is that the lump was caused by grains of coral growing under my skin (on the top of my foot).

    Rating: 5.0/5. From 3 votes.
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  3. “This last was basically a series of photographs showing – in graphic detail – what can happen when one is gashed on the ankle by a section of live coral. The accompanying notes detailed the sufferer of the resulting coral infestation, where coral polyps entered the bloodstream in this warm & moist, nutrient-rich environment, attached themselves to the ankle bone of this patient and proceeded to multiply. ”

    I am a coral biologist. The above is not how corals work. Coral polyps are millimeters across, so it would be hard for them to enter the bloodstream at all. They would also not survive in blood, see the Doc’s answers above. Finally, coral polyps when severed from the parent colony can take weeks to attach to substrate. I don’t doubt that there was something on the ankle, but it wasn’t coral polyps.

    Rating: 3.4/5. From 5 votes.
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  4. Guam, 1979 fire coral in back….went to the base emergency room…. ‘oh, we’re going to have to scrub the wound or youll have coral growing in your body’.

    Rating: 4.0/5. From 7 votes.
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  5. I don’t know about corals except the occasional sting. Ido have several aquariums and have seen life that has been regulated to certain condition thrive way beyond the norm. One such creature is a sea sponge. I have removed many tiny pineapple sponges from my tank by changing water ; usually the first stages of a newer tank by pouring them down the sink. These creatures are usually the size of a cotton swab tip. Imagine my surprise when the sink is clogged months later by sponges the size of softballs backing up my plumbing. Without regulation of water temp, nutrients or light they thrived beyond measure.
    Secondly I did have a friend who jumped off a rock on the California coast only to scrape his knee badly. A week later he went to the doctor with very strange patterns and discolorations to his leg only to find krill eggs growing on his raw skin with other ” fauna”. Legs fine now but it was gross. I do have koi too and treat them with saltwater when fungus grows on them. I just pour it in the pond and they are cured. My point is that we give nature these boundaries that are crossed all the time. I really believe I have witnessed a few but there are many more that are more remarkable than my examples. I applaud true divers and wish I was as brave. I will say though through fragging corals to inhaling sulfur hydroxide from a tank accidentally sea life dangers are real.

    Rating: 4.0/5. From 6 votes.
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  6. hi Doc,
    Guess I can’t argue with your medical maths, so will agree that the aforementioned conical, calceous excision was not coral based – though it was definitely thriving in the patient’s bloodstream and firmly attached to his ankle bone… You’d doubtless disagree then with the local native method of treating Stonefish stings that we were also warned about on Gan… We were told then that if a local stepped on a stonefish and could be removed from the water before drowning, he’d be tied firmly to a palm tree and left there overnight.
    If he (sea fishing was a males-only activity then and always barefoot), survived the ordeal, he’d probably make a full recovery. No mention was made of immersing the affected limb in hot water to break down the toxin, as we know to do now, but it must have been an unpleasant experience, to say the least!

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  7. Hey King of Thieves,

    I don’t doubt that something was excised from the ankle of a teenager from a small, remote atoll in the Maldives under the medical expertise & equipment that prevailed in that area in the ‘60s. Or that the procedure left a large, conical, surgical hole at the excision site. However, in the absence of scientific confirmation that the material excised was in fact composed of living coral, this anecdote is in no way “proof positive” of the growth of coral polys within the human body. Was the removed material subject to histological or any other sort of reasonable confirmative examination?

    As to what, exactly, was excised, I can only refer to the facts as we know them:

    1. Average salinity of the Atlantic & Pacific Oceans is ~3.5%. The vast majority of tropical saltwater corals tolerate only a fairly narrow range of salinity; they grow best with a salinity between ~3-4%. The salinity of human blood is ~0.9%.

    2. Optimal temperature for tropical coral growth is 73-77°F, although temps between 61-95°F can be tolerated by a small number of species. The body temp of a human is 98.6°F.

    3. Light is critical in maintaining the symbiotic association between tropical corals and the symbiotic algae (zooxanthellae) that assist in nourishing them. There is negligible to no light below the skin of the human body.

    4. pH measures hydrogen by factors of ten, The ideal pH for tropical coral polyp growth is within the ~8.3-8.5 range. The pH of normal human arterial blood is ~7.35-7.45.



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  8. Hi Doc,
    Thanks for the reply, though if what you aver is accurate, I have been badly misinformed – from an early age – as to my Autoloclean origins…I may have been labouring under the misapprehension that “A Picker-up of Unconsidered Trifles” was what lay behind dear olde William’s nomenclature – but no matter.
    As to your assertion that coral polyps could not thrive in the human body, I can only report on what was identified, diagnosed, monitored, catalogued, photographed and – eventually – excised from the ankle of this Maldivian teenager from Addu Atoll, back in the 60’s.
    I believe that the current owners/occupants of Gan have repaired most of the damage inflicted by the Maldivian government after the Royal Air Force left in 1976 – which back then was a perfect illustration of “Sour-grapes syndrome”. Political pique aside, when the RAF left, the (then), Medical Officer on the island remained behind with his nurse wife, to ensure continuation of treatment for the local islander population. As the only MD for many miles around, he – and the Medical centre itself – would have remained relatively unscathed as marauding Maldivian military forces from Male trashed the aviation fuel farm and many of the other buildings and infrastructure abandoned when we climbed aboard the last VC-10 or RFA in 1976.
    So it is a reasonable assumption that this pragmatic property protection would have continued throughout the “quiet” years and decades from that time until developers and Male politicians finally reached an accomodation over the island’s accomodation. Which in turn may mean that such medical records as existed for all to see and learn from back then still exist today – including the conical coral plug surgically removed from said patient’s ankle, which was retained, preserved in a glass jar (presumably in Formalin or similar substance), then displayed as a caution to all who ventured out upon the coral reefs in their spare time.
    Whilst I respect your professional qualifications and the medical experience gained in your chosen field, even a minor diving medic like me cannot argue with the evidence of what was (then), observed by my own eyes, in a jar and with accompanying photo sequence, in the Medical Centre, on the island of Gan, in 1975.
    So, in this case, we must agree to disagree.
    Keep those bootees on…

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  9. Hi King of Thieves,

    Well, I guess that anything is possible, but your assertion is extremely debatable.

    For openers:

    1. The vast majority of tropical coral polyps thrive best in water temps between 76°F-84°F, although many can apparently can survive in extended temp ranges of 64-91F. However, I am unaware of any reports of them surviving ln, not to mention growing, in temps as high as the 98.6F of the human body.

    2. Polyp coral does best with moderate light, although some can tolerate low light. No tropical polyp coral grows in near complete darkness such as would be found within the vast majority of the human circulatory system & sub-dermal body areas.

    3. To a coral polyp, “nutrient-rich” means an abundance of plankton to eat and/or symbiotic zooxanthellae that produce nutrients through photosynthesis. Human blood has none of these. And this does not address the need for adequate circulating calcium carbonate with which to form their skeletons.

    4. The ideal pH for tropical coral polyp growth is within the 8.3-8.5 range. The pH of normal human arterial blood is ~7.35-7.45. Given that pH measures hydrogen by factors of ten, moving pH from the 7.4-7.5 to the 8.3-8.5 range is quite significant. Tropical coral polyps could not thrive in pH’s within the range of normal human plasma values.

    Now, an infection related to another microorganism(s) introduced by a coral scrape/cut that infects a nearby bony structure & causes a lesion that later requires excision I can buy.

    And we can entirely agree that wearing proper diving protection on exposed skin areas & receiving appropriate wound care are prudent.



    Rating: 4.2/5. From 5 votes.
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  10. Dear Doc,
    Though not an MD, I am a diver and licensed aircraft engineer and have travelled around the globe in pursuit of both activities.
    One of my overseas jaunts involved staying on a little coral island at the southernmost side of the southernmost atoll in the Maldives, mending & maintaining passing aircraft for the Royal Air Force, back in the mid-70’s.
    On arrival at RAF Gan, we spent more than the usual amount of time being shown some of the perils pursuant to living on a tropical island in the Indian Ocean – one of the most memorable being a conducted tour of the Institute of Pathological and Tropical Medicine’s outpost, attached to the medical centre on Gan. There one was shown Stonefish in jars (beware barefoot walking in water), 30-foot tapeworms removed from unfortunate locals and – one of their prized exhibits – a salutary warning tale about what happens when one ignores coral cuts.
    This last was basically a series of photographs showing – in graphic detail – what can happen when one is gashed on the ankle by a section of live coral. The accompanying notes detailed the sufferer of the resulting coral infestation, where coral polyps entered the bloodstream in this warm & moist, nutrient-rich environment, attached themselves to the ankle bone of this patient and proceeded to multiply. The final photos showed – in colour – a large, conical, surgical excision of the affected ankle – leaving a large hole in said patient’s lower extremity.
    Needless to say, after seeing that kind of visual evidence, anyone walking around in the popular rock pools off the south side of the island (an activity otherwise known as “Oggin-Troggin”), did so with something more substantial than flip-flops on their feet. They also, invariably, sought immediate medical assistance if any coral cuts broke the skin & drew blood. Said treatment was often carried out on the patio outside one’s billet, after a cold beverage or three had been consumed to dull the pain of the ensuing swabbing with iodine, hydrogen peroxide or merthiolate (spell-check required for that last one), after a meticulous inspection of the open would and removal of any coral fragments had been carried out with alcohol-sterilized forceps…
    … A practice that I continued (though in somewhat more hygienic surroundings), during my six sailing & diving years in the Sultanate of Oman – another tropical paradise known for its corals.
    And the point of this preamble…? You may think that coral polyps cannot grow inside a human – but I have seen proof positive to the contrary.
    Whatever your beliefs in this argument and while debating the issue after being coral-cut, with an open wound oozing blood on one or more of your extremities, just pop along to a first-aid post and have the current treatment applied. Whether one believes in coral polyp sub-dermal propagation or not, having someone clean the wound, remove foreign bodies and apply the appropriate anti-infection regime is always a good idea.
    Safe diving – and always wear bootees when diving warmer waters…!

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  11. I once had a tomato seed sprout in a dental cavity (I take better care of my teeth now!)

    Also found the small pliers (the tweezers were useless) on my swiss army knife great for removing sea urchin spine fragments from the knee of a fellow diver (I can’t remember if he was wearing a shorty or they’d penetrated his thin wetsuit). It was Egypt, warm and humid, and I was worried (as DocVikingo is) they’d become infected and then nastier…

    Rating: 3.0/5. From 2 votes.
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  12. You’re right! It started with an insignificant scratch on my ankle from presumably coral during a walk out through the shallows to a boat. That was March. It just got worse with haematomas breaking out on my calfs for which I still have the scars.

    Rating: 3.7/5. From 3 votes.
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  13. Bummer, John.

    However, I can pretty much guarantee you that the infectious agent proper wasn’t coral polyps per se growing in or tracking though your lymphatic system. Far more likely is that the infectious agent was contracted though contact with a coral, such as via a scrape or other violation of the skin. Breaches of the skin u/w can allow for entry of Vibrio species (e.g., vulnificus, alginolyticus, parahaemolyticus) which can cause cellulitis & necrotizing fasciitis (aka “flesh-eating disease”), potentially very grave bacterial infections, indeed. As for lymphatic system involvement with Vibrio, this certainly can & does occur. This is known as septicemia, more specifically bacteremia (aka “blood poisoning”). A sure tip off of this is a red streak or streaks running along an extremity.

    Of course coral scrapes/punctures also can allow for the entry of other infectious agents, such as staphylococcal species that may be acquired in contaminated water or on land.

    Sounds like you were lucky, as such infections are alarmingly often fatal.



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  14. I spent 1999 with coral infection tracking through my lymphatic system culminating in life-saving surgery in November that almost lost me my right leg.

    Rating: 4.2/5. From 5 votes.
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