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Dangerous Marine Life 2


Dr Oliver Sykes  In the dangerous marine life series, this month I will cover injected toxins.


Cone shells or snails have attractive shells, and may be picked up by children or visitors to the reef who may be unaware of the danger. The cones possess a detachable, dart-like tooth, with venom that can cause sustained muscle contractions, numbness and weakness.

Symptoms: Small puncture wound with localized blanching, cyanosis and swelling. Severe pain, numbness, and tingling of the mouth and lips. Sometimes there is difficulty breathing and paralysis.

Treatment: Immobilize the limb, apply a pressure dressing, administer CPR if needed. Cleanse the puncture site, give analgesics and give tetanus prevention. Be prepared to support and monitor rate and depth of breathing. There is no anti-venom.



The salivary glands of the blue-ringed octopus produce venom.

Symptoms: The bite is usually painless and is followed by painless paralysis. Beginning with abnormal sensations of the mouth, neck and head, then nausea, vomiting, shortness of breath and sometimes lack of respirations. There can be visual disturbances, impaired speech and swallowing, and generalized weakness and paralysis. The duration is from 4 to 12 hours.

Treatment: Immobilize the limb, apply pressure dressings, cleanse the bite, treat for tetanus and monitor rate and depth of breathing.



These possess a serrated bony spine at the base of the dorsal surface of the tail. Most injuries occur when the ray is stepped on.

Symptoms: Intense pain at the site; there is local loss of blood supply and swelling. Edges are jagged and may contain pieces of spine. Therefore secondary infection is common. Systemic effects include salivation, sweating, vomiting, diarrhoea, cramps, low blood pressure, and fast heart rate.

Treatment: Irrigate and remove remaining spine. Immerse in hot (50 C) water until pain subsides. Give local or systemic pain relief. Cleanse, debride and suture the wound. Give tetanus protection, infection prophylaxis and monitor heart rate, blood pressure, rate and depth of breathing.



Catfish are a common and widespread group of fish, found in rivers, estuaries, seagrass flats, mud flats and reefs. They are furnished with three venomous spines – one on the back and one on each side. These spines are very sharp and easily effect a serious injury, resulting in severe pain at the site. The pain usually only lasts a few hours The fins have a complex toxin which is believed to be destroyed at temperatures above 40 C.

Symptoms: Intense pain out of proportion for the physical injury, generalised symptoms are rare, including muscle cramps, tremor, fatigue, syncope and even cardiovascular collapse.

Treatment: Immerse in hot (50 C) water, cleansing of the wound and liberal irrigation with hot water. Give tetanus protection and antibiotics that cover Vibrio vulnificus. Severe allergic reactions can occur.



There are many species, including lionfish and stonefish. The venom is similar to stingray and is destroyed over 50 C. An antivenin is available through the Australia Commonwealth Serum Lab.

Symptoms: Immediate intense pain, redness, swelling, cyanosis, nausea, vomiting, low blood pressure, delirium and cardiovascular collapse.

Treatment: Irrigate and remove debris. Immerse in hot (50 C) water. Give analgesia, antibiotics, tetanus and antivenin if available.



The sea snake is an inquisitive but usually non-aggressive air-breathing snake. Sea snakes are readily identified by their flattened tails and valvular nostrils. The venom is extremely toxic and, while not destroyed by heat, many bites are not envenomated.

Symptoms: No symptoms for10 minutes to 6-8 hours post bite then there is malaise, anxiety and stiffness, aching and paralysis, especially of the jaw and eye lids. Ten percent of untreated cases are fatal.

Treatment: Immobilize the site of the bite. Hospitalize, obtain the antivenin and give CPR if needed. Try polyvalent land snake anti-venom if specific anti-venom is not available. Haemodialysis can be helpful and respiratory support is often needed.


Question 1

What is venom?


Venom is made up of poisonous chemicals called toxins. Many animals have developed ways of injecting venom into other animals. When the toxins in the venom are absorbed into an animal’s body, they have a harmful effect on that animal. Venom is part of some creatures’ survival kit-they use their toxic weapons to survive. Some animals inject venom to gather and kill their food. Other animals use it to repel their attackers. Some animals use venom for both attack and defence.


Question 2

How do anti venoms work?


Anti-venoms are purified antibodies which act as a kind of molecular sponge to soak up venoms or venom components (toxins). The most commonly used animal in the production of Australian anti-venoms is the horse. Sheep, rabbits and dogs are also currently used in Australia. Venom is obtained in a number of different ways. Snakes and funnel web spiders are milked for their venom. Stonefish, red back spider and box jellyfish venoms are extracted from dissected glands and tissues. This can be a dangerous process


Question 3

What is a pressure dressing for?


The principle of pressure-immobilisation bandaging as a first aid measure is to prevent the spread of toxins through the body. This is done by applying enough pressure to compress the lymph vessels, and by preventing movement of the affected limb. Correct application of the technique can buy valuable time to get the patient to medical assistance.


Question 4

Which antibiotics should be used initially?


Tetracycline deriviatives, chloramphenicol, penicillin and aminoglycosides are useful broad spectrum antibiotics that will also cover Vibrio vulnificus.


Question 5

What do the blue rings on the blue ringed octopus mean?


The usual colour of this animal is a mottled brown, but when disturbed, bright blue rings appear on its skin, warning of the danger of a bite.


Question 6

Where can I find more information?


Australian venom research unit


A key activity of the Unit is to provide medical advice on envenomations, anti-venoms and related issues to doctors, veterinarians, paramedical staff and poisons information centres, as well as zoos, reptile parks and keepers, various workplaces, government departments and the military, Australia-wide and internationally. A 24 hour consultancy service is available for DOCTORS AND PARAMEDICAL STAFF ONLY. The Unit also aims to increase public awareness of the dangers of venomous creatures, and the first aid measures for such bites and stings. It also works closely with the World Health Organisation in matters of anti-venom standardisation as well as patient care.