A diver in Indonesia was left with an unusual burning rash after being "pushed into" fire coral while diving in tropical waters.
The diver revealed images of the rash in a Reddit post in March under the username buckbuckmow. The pictures show red patches and dark scabs on the person's knee.
In a caption shared with the images, the poster said: "Nearly a week ago I scraped my knee on what I believe was fire coral in Indonesia. It burned like crazy for the whole dive and afterwards. The first pic is from the day I got home (last Thursday) and this morning. It has become more painful, and the scraped areas are turning black. Has anyone had this experience?..."
Images of a knee rash that a diver in Indonesia was left with after coming into contact with what's believed to be fire coral that was shared in a post on Reddit. Images of a knee rash that a diver in Indonesia was left with after coming into contact with what's believed to be fire coral that was shared in a post on Reddit. buckbuckmow on Reddit.Maria Rosa, an associate professor of biology at Connecticut College, told Newsweek: "Yes, this looks like it could be it [fire coral]," but noted that this is "not 'coral poisoning.'"
She explained: "Corals and jellyfish are in the same family of animals that are defined by having 'stinging cells' known as cnidocytes. These cells are on a hair trigger and release a venom to subdue prey, such as fish, for eating."
Depending on the species and how sensitive a person is, humans who come into contact with fire corals can experience a rash "and in some severe cases even paralysis," she warned.
"Fire coral is known for creating a very uncomfortable burning sensation, hence the name," Rosa said, adding that it usually goes away after a few weeks. "It can result in a welt [an areas of skin that's raised after pressure is applied] or these types of lesions, similar to what you get if stung by a jellyfish."
What is Fire Coral?
Fire corals are not actually coral but rather "a hydrozoa undergoing two different life forms," according to the Department of Biology at Lamar University in Texas.
Hydrozoa is a subgroup of cnidarians, a group of more than 9,000 living species, mostly marine animals.
In an August 2022 article published by the U.S. National Science Foundation, marine biologist Peter Edmunds explained that fire corals have the ability to grow as sheets or as trees.
"When it's not stormy, they can produce branches and exploit the light and plankton in the water," he said. "When it's storming and everybody gets beaten up, they lose their branches but still have their sheets, which they can use to spread out and claim more territory."
Fire corals are commonly found in shallow reefs "where an optimum level of sunlight is available and a variance exists in the flow of water," Lamar University's website says. Fire corals may thrive in areas with a high and strong current, and may be found on reef faces or the edges of reefs.
Edmunds noted: "Fire corals have been around for millions of years and what they are doing is successful. I would posit that having gone this far, they are now poised to be somewhat the inheritors of the reef, while other corals, particularly stony corals, die back."
A stock image of fire coral in the Red Sea in Egypt. The fire corals are not actually coral, but rather a hydrozoa, a subgroup of cnidarians, which is a group made of more than...A stock image of fire coral in the Red Sea in Egypt. The fire corals are not actually coral, but rather a hydrozoa, a subgroup of cnidarians, which is a group made of more than 9,000 living species. iStock / Getty Images Plus
'Very Uncomfortable Burning Sensation'
According to a later comment from the poster of the latest Reddit post, the water temperature on the day of the fire coral incident was 86 degrees Fahrenheit.
"I've been diving in tropical waters like this for decades and this is the first time I've ever touched coral," the poster said, noting that they "got pushed into it [the fire coral] by another diver.
"After nearly three decades of diving...I can say with confidence that my buoyancy control is well above average. Sometimes one experiences severe currents, outside influences like other divers, etc. In my case, I was pushed into it by a diver...."
According to another later comment, the poster saw their doctor.
"He prescribed Bactrim [medication used to treat a range of bacterial infections] and told me to take an antihistamine [medication typically used to treat allergy symptoms]. The black is coagulated blood. All is well."
Redditors were shocked by the images of the rash and shared stories of similar experiences.
User kpinpdx said: "Yep looks infected. Go get some antibiotics!"
Jo_Gray wrote: "This happened to me (but snorkelling) in Mauritius! They treated it straight away with all manner of antiseptics and ointments! It still hurt like hell and was by far the longest scab to heal!"
User bryan2384 said: "Happened to me a long time ago. I had a rash for literally months."
FlipMick noted: "I had something like this when I brushed a coral with my left shin while in the Philippines. The area still itches periodically and tends to bleed a lot when I scratch it. This was 7 years ago..."
Newsweek has contacted the original poster for comment via the Reddit messaging system.
Do you have a travel-related story to share? Let us know via life@newsweek.com and your story could be featured on Newsweek.
