The greater blue-ringed octopus (Hapalochlaena lunulata) by Samantha Craven
Only my second encounter with this tiniest of terrors. The three species of blue ringed octopus contain venom so potent that it contains all these words: tetrodotoxin, 5-hydroxytryptamine, hyaluronidase, tyramine, histamine, tryptamine, octopamine,taurine, acetylcholine, and dopamine (Source).
The venom is produced by bacteria in the salivary gland and happily there is no cure. So after you’ve been bitten, when you stop breathing and your hear stops beating, you better hope that your friends are good enough to manually respirate you until you get to hospital and/or metabolize all those words out.
There is always the fact that you need never touch one. Or poke it.
Spot the scorpionfish!
Photo by Samantha Craven
Click the link - it’s a bad ass video!
Cone snails are the largest known genus of invertebrates. They eat molluscs, worms or fish, which they catch using “harpoon-like” spears that are loaded with a venom containing up to 200 different toxins, and Conus geographus (featured in the BBC video) is the most venomous of all.
Cone snails are efficient little factories of death. They manufacture and store little hollow harpoons in a sac in their body, and they have another sac which synthesises venom.
The harpoons are loaded into the proboscis and then armed with venom when they sense their prey.
Fish-eating cone snails like the Conus geographus only use a harpoon once. They swallow it while digesting their prey.
The venom is neurotoxic, essentially working to paralyse their victims. The toxins have been researched and developed into a painkiller for cancer patients and is said to have similar properties to morphine.
Irukandji Syndrome
In 1964, Jack Barnes confirmed that the cause of the syndrome was a sting from a small box jellyfish: the Irukandji jellyfish. In order to prove that the jellyfish was the cause of the syndrome, he captured one and deliberately stung himself, his son, and a local lifeguard, and observed the symptoms.
Irukandji syndrome is produced by a small amount of venom and includes severe pains at various parts of the body (typically excruciating muscle cramps in the arms and legs, severe pain in the back and kidneys, a burning sensation of the skin and face), headaches, nausea, restlessness, sweating, vomiting, an increase in heart rate and blood pressure, and psychological phenomena such as the feeling of impending doom. The syndrome is in part caused by release of catecholamines. The venom contains a sodium channel modulator.
The sting is moderately irritating; the severe syndrome is delayed for 5–120 minutes (30 minutes on average). The condition is rarely fatal, but if immediate medical action is not taken, within only 20 minutes the victim could go into cardiac arrest and die.
The symptoms range from hours to weeks, and victims usually require hospitalisation. As with other box jellyfish, vinegar will deactivate unfired nematocysts on the skin but has no effect on the venom already in the body.
Irukandji Jellyfish
There are actually two species of Jellyfish (Carukia barnesi and the recently discovered Malo kingi) - and they are thought to be the most venomous creatures in the world.
Their bite is definitely bigger than their bark - its size is roughly no larger than a cubic centimetre (1 cm³) and yet its venom is very powerful, 100 times as potent as that of a cobra and 1,000 times as potent as that of a tarantula.
The Irukandji are unique from other jellies in two prominent ways: they have stingers on their ‘bell’ as well as their tentacles, and they have the ability to fire stingers from the tips and inject venom.
Irukandji jellyfish were at one time thought to be in the northern waters of Australia only. Since then, according to a National Geographic documentary on jellyfish, the species has been found in waters as far north as the British Isles, Japan, the Florida coast of the United States.
This is how I ended my snorkel yesterday….
A friend called me over to the shallows as I was walking in, he had found a Blue Ring Octopus (genus Hapalochlaena) - one of the most venomous animals in the world. This one was just over an inch long. When the octopus is agitated, the brown patches darken dramatically, and iridescent blue rings or clumps of rings appear and pulsate within the maculae. This photo [by Dan Geary] is of it flashing at us when we got a bit close. The venom is strong enough to kill a humans and there is no anti-venom. The octopus produces venom that contains tetrodotoxin, 5-hydroxytryptamine, hyaluronidase, tyramine, histamine, tryptamine, octopamine, taurine, acetylcholine, and dopamine. identical to tetrodotoxin, a neurotoxin which is also found in pufferfish and cone snails that is 10,000 times more toxic than cyanide. Tetrodotoxin blocks sodium channels, causing motor paralysis and respiratory arrest within minutes of exposure, leading to cardiac arrest due to a lack of oxygen. The toxin is produced by bacteria in the salivary glands of the octopus.
Common Lionfish (Pterois volitans) by Paul Sutten
Scorpionfish - Bohol, Philippines
Red centipede ~ 20cm long. Langkawi, Malaysia.
Komodo ‘11: Day Five: Crystal Rock
Tassled Scorpion fish [Scorpaenopsis oxycephala].
As the name suggests, scorpionfish have a type of “sting” in the form of sharp spines coated with venomous mucus.

