However, the bite of the spiderfish, or Trachinus draco, is not always deadly. What does the fatal outcome depend on? “ Accidents with this fish are, fundamentally, poisonings in one of these situations : the bather sticks one of the spines of the spider fish by stamping it while walking on the sand in the water; the fisherman sticks a thorn in his hand when handling it; And, in mating season, this fish can attack.
he spider fish belongs to the Trachinidae family of fish , not too large – it measures between 10 and 30 centimeters long, although some reach 50 – and has a grayish yellow color, making it very attractive for people who practice snorkeling and diving. . The Trachinus draco , another of the names by which the spider fish is known, likes cold waters better and is present, in addition to the Mediterranean Sea, the Cantabrian Sea and the Atlantic Ocean.
This fish usually hides in the water under the sand and feeds on small fish that it ambushes. From a toxicological point of view, it has a very effective defensive apparatus for predators that want to swallow them, based on spines (between five and eight dorsal and two others on both sides of the head protecting their eyes) that are connected to vesicles that store poison . When the fish sticks the spine and it breaks, it releases the poison.
Salgado gives more details about this poison, commenting that “all poisons in the animal kingdom have protein parts and other types of chemical molecules, such as serotonin, histamine, adrenaline and noradrenaline, which can cause an anaphylactoid reaction.” Furthermore, in Trachinus draco , dracotoxin is a protein toxin that can cause neurological and blood disorders. The venom has proteins that will cause a destruction in the tissue where it has been inoculated, generating wounds that take time to heal.
Although there are not many cases of death from this cause in the scientific literature, Salgado recalls the case of another patient who died in 1999 due to the bite of a spider fish. It was an 18-year-old boy, of British nationality, who was snorkeling in shallow waters off the coast of Palma de Mallorca. He approached a spider fish and was unlucky enough to get stung in a vein in his left leg , the poison reaching directly into the circulatory system. Finally, he suffered a cardiorespiratory arrest. “This shows that the danger comes from the area where the animal is bitten,” says the expert.
For this reason, Salgado’s recommendation to prevent the bite of this animal is not to come into contact with it. This tip is for people who snorkel or dive, as the spines get through the wetsuit. The expert acknowledges that it is more difficult for bathers to avoid stepping on a spider fish that is hidden in the sand.
To distinguish the bite of this fish from that of a jellyfish
“The first symptom that appears is a very strong pain , which usually reaches the peak of intensity within half an hour of receiving the bite. The person himself perceives that the area where the spider fish has bitten him is reddened. In some cases there is a bit of a thorn stuck in it, which will have to be removed, ”says the Clinic specialist.
Due to the effect of the poison, sweating, low blood pressure, the urge to vomit, decreased level of consciousness, seizures or cardiorespiratory arrest can also occur in the most severe cases.
In Salgado’s experience, there are few cases of spider fish bites per year, mentioning that this year he has only seen one patient in his hospital.
How to deal with a spider fish bite and its venom
Interestingly, this poison is inactivated by heat because its toxin is heat labile. For this reason, says the ER doctor, “we would have to introduce the part affected by the sting in very hot water as soon as possible , at a temperature of about 43 degrees Celsius, for between 30 and 90 minutes .”
You also have to put general analgesia. The pain suffered by the patient is so intense that, sometimes, even morphine has to be added. Calcium gluconate is sometimes given intravenously when nausea, vomiting, and chest pain are present.
If the patient suffers an anaphylactoid reaction caused by the venom, they will be given corticosteroids at very high doses and supportive treatment.
To manage the wound, in addition to checking that no part of the spine has remained inside the body of the affected person, it is necessary to give the tetanus vaccine (if it has not been received in the last 10 years) and give antibiotic coverage by route oral if the wounds are deep , apart from the initial local disinfection.
Care to take into account after administering the treatment
In the days after a spider fish bite, “in addition to continuing with the prescribed antibiotic treatment and pain relievers, some rest is recommended and the limb that has the injury is raised. The patient must receive follow-up by Toxicology or by his primary care doctor ”, indicates Salgado.
It is important to know that the wound produced on the skin by the spider fish takes a long time to heal and can last up to three months, although the most common is that it closes in one or two months. The wound is first red in color, which then turns black and appears with craters or ulcers on the skin.