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Great Barrier Reef
Coral Facts
Some Of the Dangers

  Great Barrier Reef

Things that Hurt on the Reef. ...continued
By Walt Deas


These unaggressive individuals don’t move very fast. But if the current or surge takes you into one of them, you undoubtedly will! Sea urchins are pincushion like creatures (allied to the starfish) that populate reefs worldwide. Many species have short, blunt spines. Other sport long, sharp spines, with very sharp tips, which act as natural hypodermic needles. They are generally brittle and break off easily beneath the skin. Toxin injected by the urchin’s venom glands can cause intense pain.

One species the Toxopneusidae have short thick spines pushing through a display of flower-like pedicellariae. These have hook-like jaws and can deliver venom, which can result in severe pain, respiratory distress and paralysis. Deaths have been reported.

Immersion of the wounded area in hot water frequently provides pain relief. A local anaesthesia alleviates the pain rapidly. Complete removal of the spines usually means surgical exploration of the wounds. Local antibiotic therapy after spine removal reduces secondary infection. In the Seychelles their solution is to immerse the punctured area in as hot oil as you can stand, or drip hot candle wax on them!

It is a rare diver who has never had a run in with a sea urchin, and quite often the offending creature is chopped up to feed the fishes. Don’t, as you are upsetting the delicate balance of the reef. They do have a role to play in the reef community.


(Sea Cucumbers; Beche-de-Mer; Trepang or Sea Slug.)

These sausage-shaped scavengers are quite common on most reefs. Some exude white sticky threads, these threads and a skin mucus can cause skin and eye irritation and reportedly blindness if contact is made between these materials and the victim Some also ingest other stinging animals and may excrete these later in their own defense. There is also the toxic material called holothurin in the excreta, which can cause localised swelling. Dermatitis can occur if the sea cumber is handled a great deal.

The sea cumber also contains a toxin, which may act on the nervous and muscular systems. Still collected in quantities, mainly for the eastern markets, the toxins are removed by boiling the sea cumbers.


The molluscs comprise of the seashells, octopus and squid. The edible molluscs (oysters and other shellfish) can cause allergies, and other possibilities such as the hepatitis virus. In some cases, injuries to humans may occur from toxins produced by the molluscs themselves.

Notable among such shellfish are the prettily marked cone shells of the Indo-Pacific region. These often-beautiful creatures possess a well-developed venom apparatus, a minute harpoon, called a radula tooth, which can inject powerful venom. The fish eating cones are the most dangerous members of the group and have developed a toxin effective against vertebrates and which can be lethal to humans. Fatalities have been recorded in Australia and in the Indo-Pacific.

Only a few species of cones are known to be certainly lethal. They inject their venom by firing a dart into the flesh. These species are Conus geographus, C. textile, C. striatus, C. tulipa, C. marmoreus and a few others. The initial puncture effects may vary from painless to an excruciating pain. The area becomes swollen and can be numb to touch. Respiratory paralysis can result and eventually death.

One cone shell that is very dangerous to humans is the Geography Cone; Conus geographus it is recorded as having killed at least 12 people, there could be many unrecorded deaths. The radular dart can penetrate gloves and wetsuits.

The puncture effects can vary from painless to excruciating agony. Numbness and tingling can affect the whole body and paralysis can spread from the area of the sting. If stung apply a pressure bandage, rest the patient and summon medical assistance. Artificial respiration is the major contributor in saving a patient’s life.

The theory that picking these shells up by the blunt end doesn’t work - they can extend their proboscis around and fire or thrust the minute harpoon, called a radula tooth into the collector’s hand. Do not place live cone shells in your wetsuit or in a pocket as has been done, as the harpoon can pierce neoprene and clothing. Don’t touch!

Shells to be treated with extreme respect:

Conus catus (Cat Cone).
Conus ermineus [Agate or Tortoise Cone).
Conus gloria-maris (Glory of the Sea).
Conus straitus (Straited Cone).
Conus tulipa (Tulip Cone).
Conus marmoreus (Marbled Cone).

Conus geographus (Geographer Cone).
Conus omaria (Pearled Cone).
Conus parius (Parian Cone).
Conus segravei (Segrave’s Cone).
Conus textile (Textile Cone).

The innocent looking cone shell has claimed the life of many incautious shell collectors by injecting a lethal cocktail of venoms. But the very qualities that kill may soon be used to cure. The reason is the fishy ancestry of humans. The cone has developed a highly specialised arsenal of potent neurotoxins to protect itself from being eaten by fish. As humans have inherited a similar nervous system to fish, this is why the cones venom works on humans.

The combination of peptides that cones inject has indicated to scientists that they could have very useful effects in nerve responses, blood vessels or muscles. The scientists are studying the effects of the substances extracted from the cones and then attempt to devise drugs that mimic their action - but more slowly and with greater specificity, to create a useful drug. It is expected that new drugs can be found to treat cardiac conditions, to relax muscles, to treat nerve conditions such as epilepsy, schizophrenia and even Alzheimer’s disease. It would seem that tropical waters could be a gold mine for new biomedical drugs.

Another shell to be careful of is the oyster, its jagged sharp edges can cause painful cuts, which often become infected.

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