Lesson 1, Topic 1
In Progress

Underwater Life-Related Hazards

There are multiple risks associated with contact with the various marine animals that can be found during diving. The objective of this course is not to comprehensively address all possible lesions and their treatments, but to give basic and general lines of action.


It is not always easy, after an accident, to make the identification of the fish (or other marine being) responsible for the injury, but this does not matter much, since the effects that the poisons cause and the attitude to be taken is practically the same.

Poisonous fish are rarely aggressive. Contact is most often purely accidental, due to distraction from the diver, or due to the undue handling of the fish. It must not be forgotten that even after the fish is dead, the thorns remain poisonous .

In most cases, the poison is very sensitive to heat, degrading if it is subjected to a high temperature. The application of hot water (or any other heat source) is a practical way to reduce its effect.


The initial symptoms are usually severe pain followed by a “numbness” or, on the contrary, the “hypersensitivity” of the area around the wound. Often, the intensity of pain is disproportionate to the size of the wound (very intense pain, with very small wound). The skin around the wound may become bluish and with swelling (edema), accompanied by a certain pallor of the surrounding tissues.

General symptoms include nausea, vomiting, shock status and loss of consciousness. In some cases, death may even occur.


The most logical and effective attitude is to avoid contact with any poisonous fish. Often these fish lie in holes and crevices, hidden among algae or buried in the sand, such as spiderfish.

The diver should always be careful when laying any unprotected part of the body, in particular by putting his hands inside a hole or when laying them on the bottom.


Synanceia verrucosa (stonefish), Scorpaenopsis diabolus (scorpionfish) and Pterois sp. (lionfish) are highly toxic tropical water fish. The toxins of these fish produce effects very similar to those of other poisonous fish, but often associated with more severe symptomatology , such as respiratory arrest, shock, cardiovascular collapse and even death.

In addition to the usual first aid procedures in these types of accidents, there are in hospitals antitoxins specific to these special cases. For this treatment to be applied it is necessary to inform the hospital that the injury was caused by one of these fish.

Although in our waters are not frequented by these fish, the Scorpaena porcus (rascasso-de-pintas) is quite common on our coast. This fish, very common in the rocky bottoms, is usually camouflaged among the algae and has a very powerful poison.


In most cases of accidents with rays, what happens is the diver stepping or disturbing the streak and this has a defensive movement with the tail when trying to escape, resulting in extremely painful wounds.


The typical appearance of the wound presents a pale, swollen area, with a surrounding halo of bluish hue. The main problem in these cases is that secondary infections are very common.

Systemic symptoms such as dizziness, fainting sensation, nausea, vomiting, cold sweats, difficulty breathing and shock may also appear.


The prevention and treatment of these cases are identical to those described for the generality of injuries caused by poisonous fish.


In most cases the result of contact with these beings is only a local irritation of the skin, but that can be very painful, as with the small Pelagia noctiluca (jellyfish), very common in the Azores.

The most careful cases are Sea wasp and Physalia physalis (Portuguese caravel).


In these two cases, toxins can cause severe systemic allergic reactions, which may quickly result in shock or even death (fatal cases have already been reported after contact with the Portuguese caravel).

There is also a danger of triggering an anaphylactic shock, a massive allergic reaction that endangers the life of the injured person. This symptom is more frequent in people who already have a clinical history of allergic manifestations.

Because it is difficult to predict the occurrence of an anaphylactic shock and in view of the severity that this situation represents, it is very important to keep the injured person under surveillance and it is justified to send them immediately to the Hospital.


Of course prevention in this case is very important. Therefore, the diver should be aware of the presence of these animals to avoid accidental contact, especially with unprotected parts of the body. Even with the body protected, contact is to be avoided, because the burning cells that are trapped in the suit can still cause burns.
Rubbing the wound with sand does not produce any relief and can even lead to the release of more toxins if there are still remnants of tentacles on the skin.


Local treatment for pain relief may include topical steroids, anesthetic ointments, and antihistaminic ointments, or even systemic analgesics and antihistamines.


Due to its sometimes cutting or abraziva structure, contact with coral can result in important wounds that sometimes take a long time to heal, often arising secondary infections. In addition, some corals have hive cells, which can cause severe burns, as with Millepora platyphylla (coral-fire).

Wounds resulting from contact with coral should be disinfected, kept clean and guarded. In some cases, observation and treatment by health professionals may even be justified, especially when coral is urticante.

Prevention, once again, is done by avoiding contact. As a precaution, the diver should always wear protective clothing, even in warm waters.


In our waters there are no reports of shark attacks. The species here are pelagic and are far from the coastal areas frequented by divers. Even where these animals abound, attacks on divers are rare (statistics in Australia show that diving accidents are much more numerous than shark attacks).

The reasons for a shark’s attack are almost always unknown, although many theories are advanced, and attacks are often unpredictable.

On the other hand, the shark’s behavior before starting an attack is predictable. The animal swims in increasingly tight circles around the prey, with wide movements and with pectoral fins directed down (the normal is to be directed to the sides), and the attack may be preceded by a sudden acceleration or other behavioral change.

The injuries can be caused not only by biting but also by contact, since the shark’s skin is very rough, because it is covered with very sharp small spicules. Thus, contact with the shark can result in significant abrasions and significant bleeding.

There are a number of rules to abide by to prevent the attacks of these animals, of which the most obvious is to avoid diving in the places where they find. Don’t forget that a shark swims ever faster than any swimmer or diver.

The result of a shark attack is usually very serious, requiring urgent hospital treatment.



  • Remove the injured person from the water, pour it on a flat surface, reassure and watch, pay particular attention to the signs of shock.
  • Wash the wound (serum). Wound suction to remove poison is not effective.
  • Place the affected area in hot water (maximum temperature tolerated up to 50ÂșC) for 30 to 90 minutes. If there is intolerance to prolonged contact with hot water, make short and repeated immersions. In wounds on the face, use compresses or hot cloths.
  • Transporting the injured to the hospital, tourniquets and bandages are not advised.


  • Remove any tentacle without rubbing or scrubbing, preferably with a towel or piece of clothing.
  • Wash the wound with acetic acid (3 to 10%), to prevent the release of more toxins.


  • Controlling bleeding
  • Clean and disinfect the wound
  • Make a dressing
  • Administer the tetanyca vaccine
  • Administer topical or systemic antibiotics if justified