Kaix
08-04-2006, 01:17 PM
Beware some of the hazards of the marine environment.
The good news for divers in Asia is that the Pacific and Indian Oceans have some of the most interesting and beautiful dive sites in the world. The bad news is that, far and away, the vast majority of hazardous marine life can be found in the tropical and subtropical waters of these very same oceans.
In general, hazardous marine animals can be divided into three categories: those that cause traumatic injuries; those that are venomous; and those that are poisonous and can cause illness or death when consumed as food.
So which fish are hazardous? And how can you prevent or, in the event of an attack, treat these mishaps?
Bark Worse than Bite
Legendary in popular literature, movies, and the media, sharks are distributed throughout the tropical and subtropical climates. Of more than 300 species, only a handful is "hazardous". Sharks are extremely fast swimmers and can detect blood in the water at a concentration of one part per million.
While many divers possess an innate fear of sharks, the chances of a shark attack are extremely small. Shark attacks are generally felt to be in error: disruptionsin the water caused by splashing about, and excursions from the surface to depth while wearing a dark coloured wetsuit (and perhaps looking like a natural source of food to the shark, a marine mammal) can both attract the attention of a shark. Shark attacks more commonly involve surfers, freedivers, and swimmers. Sharks feed more often at dusk, and attacks tend to be more frequent when the water temperature reaches 20ºC or warmer.
Sharks preparing to attack prey may bump up against it, causing injury from the contact. A shark may also use a ‘bite and spit’ approach, particularly if the shark is concerned the prey may fight back. Injuries can vary in appearance: scratches and scrapes may be present from contact with the shark’s skin; or characteristic crescentshaped bites with crushing injuries to bone and even amputations of the limbs may occur. First-aid should include stopping the bleeding with direct pressure or a tourniquet. Transporting the victim to an appropriate medical care facility as quickly as possible is critical.
The best approach to surviving shark attacks is prevention. Swimming areas in locations where sharks are plentiful are often enclosed by nets. Being part of a group decreases the chances of a shark attack. Also, sharks are more likely to attack a spearfisherman, or a diver wearing a catch bag. In the end, there’s no logical reason to avoid shark encounters while diving; sharks are beautiful animals and fascinating to watch.
Rather docile animals, moray eels can grow up to four metres in length, and have mouths that contain numerous sharp teeth. They don’t possess the greatest eyesight and have difficulty distinguishing between a diver’s hand and food. Bites may result in large wounds that may become infected. Prevention, of course, is to keep hands or other body parts away from the eel’s mouth and avoid provoking the eel. Many bites occur when divers attempt to feed eels by hand.
Marine mammals, like whales, seals, otters, and sea lions rarely pose a hazard to divers. Barracuda have a menacing appearance in the water, mostly due to their large teeth and long bodies; they’ve been known to be attracted to shiny, reflective objects such as metal chains and jewellery. I’ve seen a few bites from barracuda on the upper bodies and hands of divers. The key to avoiding injuries from all of these biting animals is to avoid placing yourself in a position where you increase the chances of being bitten.
Poison Ivy
Another marine animal feared perhaps more than it deserves to be, the sea snake can stay below the surface for prolonged periods. While its venom is extremely toxic (two to 10 times more potent than the venom of a cobra) and a bite potentially fatal, the snake’s mouth is small and its venom delivery system inefficient – many bites result in little or no envenomation. The sea snake generally will not aggressively attack divers and will bite only if it’s grabbed or feels threatened.
Most bites occur when a sea snake is brought up by a fisherman as "bycatch". The bite may consist of two to 20 puncture marks from the teeth. Initial symptoms include generalised weakness and nausea, but paralysis may set in. If the bite is fatal, death is typically because the breathing muscles become paralysed (a common theme, as you will see). Initial first-aid should include pressure dressings covering the wound as well as above and below the bite, immobilisation of the arm or leg, and getting the victim to medical care. Specific antivenins are available but land snake antivenin is also used.
Found in the Western Pacific Ocean and the waters off Australia, the blue-ring octopus is small, seldom growing larger than 15 cm in size. They’re so named because of the small blue rings distributed over their body and tentacles that become more prominent when the animal feels threatened or angry. The blue-ring octopus has a bite, which may be painless and even go unnoticed until the area turns red and swells. The bite contains a toxin similar to tetrodotoxin, a chemical that can cause weakness and paralysis. The risk here is paralysis of the muscles, particularly those used to breathe. Rapid medical care is essential.
Among the more common run-ins divers suffer are with scorpionfish, lionfish, as well the ugly stonefish. Stonefish are well camouflaged on the ocean floor, and grabbing or stepping on one is easy if a diver’s not careful. Scorpionfish can grow as long as 40 cm and have 13 sharp dorsal spines that can easily break the skin. A reaction to scorpionfish venom can be just local pain associated with the wound, but may also include a drop in blood pressure, sweats, and paralysis of the breathing muscles. Treatment includes immediately soaking the envenomation site in hot (up to 40ºC) water, which breaks down the toxin. A specific antivenin is available for serious cases.
Cone shells are very colourful yet, paradoxically, dangerous. They have a long appendage (called a proboscis) that features several teeth on the end, allowing for a venomous bite. For obvious reasons, most bites are on the hands. The venom causes muscle weakness or paralysis, and fatal bites are due to paralysis of the muscles used for breathing. Preventive measures include educating divers on which shells are potentially dangerous or, better yet, advising divers not to pick up shells of any kind.
With a long spine on its tail, a stingray can envenomate a diver by swinging its tail into an extremity. The spine is serrated and makes a jagged wound on the skin. The initial symptom is pain, but an irregular heartbeat or gastrointestinal upset may occur.
Corals, sponges, and sea urchins can inflict superficial wounds – like scratches – that result from brushing up against coral, or deep puncture wounds, as is the case with sea urchins. These marine animals actually possess venom that makes the injuries they cause more painful. Additionally, a foreign body may be retained within the wound, putting the diver at an increased risk for infection. Treatment includes thorough cleansing of the wound and ensuring that all parts of the stinging apparatus are removed.
Obviously there’s more to dangerous marine life than can fit into one article.What’s on tap for part 2? Those ephemeral beauties, the jellyfish, and fish you don’t want to see on your dinner plate.
The good news for divers in Asia is that the Pacific and Indian Oceans have some of the most interesting and beautiful dive sites in the world. The bad news is that, far and away, the vast majority of hazardous marine life can be found in the tropical and subtropical waters of these very same oceans.
In general, hazardous marine animals can be divided into three categories: those that cause traumatic injuries; those that are venomous; and those that are poisonous and can cause illness or death when consumed as food.
So which fish are hazardous? And how can you prevent or, in the event of an attack, treat these mishaps?
Bark Worse than Bite
Legendary in popular literature, movies, and the media, sharks are distributed throughout the tropical and subtropical climates. Of more than 300 species, only a handful is "hazardous". Sharks are extremely fast swimmers and can detect blood in the water at a concentration of one part per million.
While many divers possess an innate fear of sharks, the chances of a shark attack are extremely small. Shark attacks are generally felt to be in error: disruptionsin the water caused by splashing about, and excursions from the surface to depth while wearing a dark coloured wetsuit (and perhaps looking like a natural source of food to the shark, a marine mammal) can both attract the attention of a shark. Shark attacks more commonly involve surfers, freedivers, and swimmers. Sharks feed more often at dusk, and attacks tend to be more frequent when the water temperature reaches 20ºC or warmer.
Sharks preparing to attack prey may bump up against it, causing injury from the contact. A shark may also use a ‘bite and spit’ approach, particularly if the shark is concerned the prey may fight back. Injuries can vary in appearance: scratches and scrapes may be present from contact with the shark’s skin; or characteristic crescentshaped bites with crushing injuries to bone and even amputations of the limbs may occur. First-aid should include stopping the bleeding with direct pressure or a tourniquet. Transporting the victim to an appropriate medical care facility as quickly as possible is critical.
The best approach to surviving shark attacks is prevention. Swimming areas in locations where sharks are plentiful are often enclosed by nets. Being part of a group decreases the chances of a shark attack. Also, sharks are more likely to attack a spearfisherman, or a diver wearing a catch bag. In the end, there’s no logical reason to avoid shark encounters while diving; sharks are beautiful animals and fascinating to watch.
Rather docile animals, moray eels can grow up to four metres in length, and have mouths that contain numerous sharp teeth. They don’t possess the greatest eyesight and have difficulty distinguishing between a diver’s hand and food. Bites may result in large wounds that may become infected. Prevention, of course, is to keep hands or other body parts away from the eel’s mouth and avoid provoking the eel. Many bites occur when divers attempt to feed eels by hand.
Marine mammals, like whales, seals, otters, and sea lions rarely pose a hazard to divers. Barracuda have a menacing appearance in the water, mostly due to their large teeth and long bodies; they’ve been known to be attracted to shiny, reflective objects such as metal chains and jewellery. I’ve seen a few bites from barracuda on the upper bodies and hands of divers. The key to avoiding injuries from all of these biting animals is to avoid placing yourself in a position where you increase the chances of being bitten.
Poison Ivy
Another marine animal feared perhaps more than it deserves to be, the sea snake can stay below the surface for prolonged periods. While its venom is extremely toxic (two to 10 times more potent than the venom of a cobra) and a bite potentially fatal, the snake’s mouth is small and its venom delivery system inefficient – many bites result in little or no envenomation. The sea snake generally will not aggressively attack divers and will bite only if it’s grabbed or feels threatened.
Most bites occur when a sea snake is brought up by a fisherman as "bycatch". The bite may consist of two to 20 puncture marks from the teeth. Initial symptoms include generalised weakness and nausea, but paralysis may set in. If the bite is fatal, death is typically because the breathing muscles become paralysed (a common theme, as you will see). Initial first-aid should include pressure dressings covering the wound as well as above and below the bite, immobilisation of the arm or leg, and getting the victim to medical care. Specific antivenins are available but land snake antivenin is also used.
Found in the Western Pacific Ocean and the waters off Australia, the blue-ring octopus is small, seldom growing larger than 15 cm in size. They’re so named because of the small blue rings distributed over their body and tentacles that become more prominent when the animal feels threatened or angry. The blue-ring octopus has a bite, which may be painless and even go unnoticed until the area turns red and swells. The bite contains a toxin similar to tetrodotoxin, a chemical that can cause weakness and paralysis. The risk here is paralysis of the muscles, particularly those used to breathe. Rapid medical care is essential.
Among the more common run-ins divers suffer are with scorpionfish, lionfish, as well the ugly stonefish. Stonefish are well camouflaged on the ocean floor, and grabbing or stepping on one is easy if a diver’s not careful. Scorpionfish can grow as long as 40 cm and have 13 sharp dorsal spines that can easily break the skin. A reaction to scorpionfish venom can be just local pain associated with the wound, but may also include a drop in blood pressure, sweats, and paralysis of the breathing muscles. Treatment includes immediately soaking the envenomation site in hot (up to 40ºC) water, which breaks down the toxin. A specific antivenin is available for serious cases.
Cone shells are very colourful yet, paradoxically, dangerous. They have a long appendage (called a proboscis) that features several teeth on the end, allowing for a venomous bite. For obvious reasons, most bites are on the hands. The venom causes muscle weakness or paralysis, and fatal bites are due to paralysis of the muscles used for breathing. Preventive measures include educating divers on which shells are potentially dangerous or, better yet, advising divers not to pick up shells of any kind.
With a long spine on its tail, a stingray can envenomate a diver by swinging its tail into an extremity. The spine is serrated and makes a jagged wound on the skin. The initial symptom is pain, but an irregular heartbeat or gastrointestinal upset may occur.
Corals, sponges, and sea urchins can inflict superficial wounds – like scratches – that result from brushing up against coral, or deep puncture wounds, as is the case with sea urchins. These marine animals actually possess venom that makes the injuries they cause more painful. Additionally, a foreign body may be retained within the wound, putting the diver at an increased risk for infection. Treatment includes thorough cleansing of the wound and ensuring that all parts of the stinging apparatus are removed.
Obviously there’s more to dangerous marine life than can fit into one article.What’s on tap for part 2? Those ephemeral beauties, the jellyfish, and fish you don’t want to see on your dinner plate.