Marine Life Injuries

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Marine Life Injuries

Marine life injuries are thankfully very rare. They normally only occur as a form of self-defence when an animal feels in danger or under threat. Therefore most marine life injuries can be avoided through positive actions from divers. These include maintaining good buoyancy control and awareness, wearing appropriate exposure protection, not touching or disturbing marine life, and also learning about typical animal behaviours that represent warning signals for possible aggressive encounters.

Occasionally marine life can be a little unpredictable, and even the most careful and aware divers may encounter some accidental touching, so knowing how to treat the different types of marine life injuries is important knowledge for a diver. This, along with the necessary skills practice is something that is covered in the PADI Rescue Diver and PADI Divemaster courses, so you can be reassure that all of our Dive Leaders are thoroughly trained in the following procedures. You can also set your mind at rest that Master Divers maintain all of the necessary safety and first aid equipment, as well as ensuring we have suitable emergency procedures in place on all of our dive boats so we are able to deal effectively with all of the following types of marine life injuries.

Here we break down the various types of marine life injuries that may occur here, and also offer advice on how to best help a diver who has been affected. In all cases the victim should be removed from the water before First Aid treatment can be administered.


Jellyfish stings can range for mild to potentially fatal. Luckily Jellyfish around Koh Tao are rare, and the potentially fatal type of Box Jellyfish that is found around Australia is not found in these waters. However, jellyfish stings can be problematic depending the location of the sting and the size of the area affected, plus if the individual is allergic. If the patient is experiencing a strong reaction, make sure to contact EMS immediately.


First step for treatment is to remove visible tentacles carefully using tweezers. You can remove any residual nematocysts (stinging cells) with shaving foam and a razor or credit card to scrape from the skin. If you have neither, flush with sea water. Do not use fresh water as there is evidence this can trigger any remaining nematocysts to fire. For this reason, the popular urban myth of using urine is also not recommended. There is also mixed opinion on using vinegar for sting relief. Use an ice pack or hot water treatment instead for pain relief once tentacles are removed.


Venomous stings (Scorpionfish / Stonefish / Lionfish)

Koh Tao does have a few resident lionfish and scorpionfish, which thankfully are the milder of this group of envenoms marine life (stonefish injuries additionally require antivenin injections).



For scorpionfish and lionfish (as well as stonefish) stings, carefully remove any spines or fragments with tweezers. Then immerse the wound for at least 30 minutes in water as hot as the patient can handle. The venom these species inject is protein-based, and the hot water treatment affects the protein structure, causing it to break down and therefore reduces the pain from the sting. If the area affected is difficult to immerse, use a hot washcloth to treat the area.

Afterwards, treat the wound with disinfectant and take over the counter pain-relief medication. Patients who receive a sting like this should always seek medical attention in case of any complications.


Coral abrasions

These are by far the most common form of marine life injury. Koh Tao does not have any fire coral (actually not a coral at all, rather a Cnidarian like a jellyfish or anemone) which can be painful and difficult to treat. Most coral abrasions are minor and require basic wound dressing first aid and do not require emergency medical treatment, however if the wound is especially deep, or covers a large area, specialist treatment may be necessary.



It’s important to ensure the wound is thoroughly cleaned in order to reduce the risk of infection. Corals are covered in a thin layer of living organisms that come away from the structure upon contact. This can contaminate the wound meaning it takes longer to heal and is prone to infection. For this reason, divers who sustain significant coral abrasions should be monitored for fever and swollen lymph glands as well as regular signs of topical infection.


Sea urchins

Aside from the obvious puncture wounds that would be sustained from an encounter with a sea urchin, some urchin spines are venomous (although the majority at Koh Tao are not) so the victim may also feel immediate pain, swelling, burning or redness upon contact.



If contact is made, remove the spines carefully with tweezers. Urchin spines are notoriously brittle and are easy to break during removal. Clean the area thoroughly and treat with antiseptic cream. You can accelerate the breakdown of any spines remaining in the body by daily soaking of the affected area in a mix of hot water and magnesium sulphate (also known as Epsom salt).


Bites – sharks & triggers

When people think of bites from marine life they will most likely picture a shark. However shark bites are extremely rare and are even rarer within the diving community as we look nothing like the food they want to eat (as opposed to surfers or swimmers). Koh Tao has two species of sharks that are seen around the island: Black Tip Reef Sharks who eat small shrimp or reef fish – not at all like divers, and the mighty whaleshark who filter feed plankton, essentially like the cow of the ocean – again not something that divers are easily mistaken for.

Anyone who has dived around Koh Tao will probably have heard about the infamous Titan triggerfish. The triggerfish can be territorial, especially around their mating season. All divers learn to read the warning signs… the head “trigger fin” pops up to give the impression of the fish being larger that it is, and the fish will bare its teeth as a signal to swim away from the area. Heeding these signs means that the risk of sustaining a bite is minimised.



If a diver sustains a bite, standard first aid treatment for a wound applies in this situation – stem blood flow, keep the patient comfortable, and monitor for signs of shock. If the wound is mild, once the bleeding has stopped, clean and sterilise the injury and apply a non-adhesive dressing. If the wound is severe, be sure to seek immediate medical attention.

DISCLAIMER: We are divers, not medical professionals. Opinions vary and best practices for treatment change over time. If you sustain, or have concerns over any marine life injury, be sure to consult a medical professional as soon as possible.


Photo/Video credits: Billy Cloud, Elisabeth Lauwerys, Dan Lee, Rob Kelly. private.

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