There are a lot of dangerous animals can be found around us, where there on land or in the sea. Many people already knew that the dangerous animals on land, for instant rattlesnake, scorpion, and tarantula etc., but they are still lack information in dangerous creatures found in the sea. They can be categorized in four categories, named:
1. Biting and other aggressive animals;
2. Venomous fish ( stinging);
3. Animals with the ability to injet venom; and
4. Jellyfish and other venomous invertebrate.
The Blue-Ringed Octopus was classified in the phylum of mollusca, which further classified in the class of cephalopoda, since it was a squid. It is only 12-20 cm long from the top of its body to the bottom of its tentacles. An average blue-ringed octopus would weigh less than 90g. While resting, the Blue-ringed Octopus is a pale brown to yellow color depending on its surroundings. This dangerous octopus has a beautiful fluorescent bright blue ring on its body where it common name come. But, beware of its beauty because it will turn to that color when it was alarmed or threatened. So, don’t be tricked with its beauty.
Figure 1: Shows the color of the Blue-ringed Octopus when it in natural state.
Figure 2: Shows the color of blue-ringed octopus when it in alarmed state.
There are three confirmed species of Hapalochlaena,
and others are still under research:
1. Greater Blue- Ringed Octopus (Hapalochlaena lunulata)
2. Southern Blue-Ringed Octopus or Lesser Blue-Ringed Octopus (Hapalochlaena maculosa)
3. Blue-Lined Octopus (Hapalochlaena fasciata)
Genus: Hapalochlaena, Robson 1929
1. Greater Blue-Ringed Octopus
The Greater Blue-ringed Octopus (Hapalochlaena lunulata) is one of three species of blue-ringed octopus. The range of the Greater Blue-ringed Octopus spans the tropical western Pacific Ocean. It can be found from northern Australia, Papua New Guinea and the Solomon Islands, throughout the Philippines, Indonesia and Sri Lanka. The Greater Blue-Ringed Octopuses can weigh between 10 and 100 grams. It is slightly smaller than Hapalochlaena maculosa with a body less than 5 centimeter long and arms from 7 centimeter across the tentacles. Papillae that covered its body giving it a rough texture. Papillae are the small projecting body part, similar to a nipple in form.
Large iridescent blue rings cover the dorsal surfaces of the mantle and web and extend out the arms. Rings on the mantle are up to 8 mm in diameter and number fewer than 25. There is a characteristic short, horizontal iridescent blue line that runs through the eye. When at natural state, it will be faint, pale in color and thin blue rings are usually visible, but when it feel threatened, the rings become much thicker and brighter . The name "Greater Blue-Ringed" refers to the size of the rings, not the body size.
There are also variable pattern of rings can be seen on mantel of Hapalochlaena lunulata, but to determine where there is Hapalochlaena lunulata or not, we can examine its rough texture which is its characteristic.
Figure 3: The arrows show the variability of the blue rings pattern of the Hapalochlaena lunulata.
2. Southern Blue-Ringed Octopus
The Southern (Lesser) Blue-ringed octopus, Hapalochlaena maculosa, is the largest of the three confirmed species and more common found. This species is found only in the temperate waters of southern Australia, from southern Western Australia to eastern Victoria.
The dorsal surface of the mantle usually has a rough appearance covered by numerous irregularly arranged wrinkles. There are also fine, unevenly sized tubercles covering the head and mantle. While resting, the background color is a uniform grey to beige, with large light brown patches or maculae giving it specific name "Hapalochlaena maculosa". When the octopus is agitated, the brown patches darken dramatically, and iridescent blue rings or clumps of rings appear and pulsate within the maculae.
On the dorsal mantle, 10 maculae form a pattern of brown chevrons. Smaller patches dot the web and base of the arms. All eight arms are marked with approximately 10 evenly spaced brown patches that form bands running down the arms. Typically 50-60 blue rings cover the dorsal and lateral surfaces of the mantle.
Figure 4: Southern Blue-Ringed Octopus in alarmed state.
3. Blue-Lined Octopus
This small octopus is found in southeastern Australia from southern New South Wales to southern Queensland. Its mantle length can grow up to 45 mm. The dorsal surface is covered with a pattern of fine, scattered tubercles and ridges. When at rest, the background color is a uniform light grey to beige. The maculae and blue lines and rings are usually not visible. When active, the background color darkens to a deep charcoal, brown or slate grey and the maculae become very dark.
On the dorsal and lateral mantle they form streaks in a diagonal pattern similar to that found in Hapalochlaena maculosa. However, on the dorsal mantle and head intense iridescent blue lines rather than rings pulsate within each dark macula. Single blue rings or clusters of rings do appear within the brown patches on the web and arms.
It is easy to distinguish these three species of Blue-Ringed Octopus simply by observing the pattern of iridescent blue markings on the dorsal mantle and head when the animals are agitated. Hapalochlaena lunulata has a few large blue rings and a distinct blue stripe running through the eye. The rings are surrounded by dark chromatophores, but there is no pattern of dark diagonal streaks. Hapalochlaena maculosa and Hapalochlaena fasciata both have maculae on the dorsal mantle forming a chevron pattern, but Hapalochlaena maculosa has many small blue rings embedded in these dark patches while Hapalochlaena fasciata has distinct blue lines.
Figure 5: The Blue-Lined Octopus
Where it can be found?
The blue ringed octopus is found living around the temperate water coastal reef of southern Australia, from southern Western Australia to eastern Victoria at depths ranging from 0-50 m. But generally, the area which this venomous creature can be found is in shallow, sandy areas surrounding the coastal reefs of Pacific Ocean, from Australia to Japan. It is mainly found in shallow waters and in rocky pools.
Figure 6: Beware of these rocky pools, because sometimes Blue-Ringed octopus can be found here.
Figure 7: The area where Blue-Ringed Octopus can be found in Australia.
How It Feed?
The Blue-Ringed Octopus feeds primarily on small crabs, hermit crabs, shrimp, and other mollusks that it hunts during the day, by ambushing from behind and enveloping its prey with its eight arms. Using its bird-like beak, the octopus bites a hole through its victim’s shell to inject toxic saliva. With its arms and beak, the creature tears soft pieces from the prey, sucking the rest of the meat from the shell once it becomes partially digested by the saliva, but the mechanism for poisoning its victim is not well understood. Either the poison is expelled in the saliva into the water or the octopus bites its prey or predator.
How It Can be Dangerous?
A Blue Ringed Octopus was not even known to be dangerous until 1954. It all started in Darwin when a young sailor started to head back to shore after going spear fishing with a friend. He placed the blue ringed octopus on his shoulder for a few minutes. He did not realise that he had been bitten. Shortly afterwards his mouth became dry and he found it difficult to breathe. This was followed by nausea and vomiting. He was immediately taken to the Darwin hospital. He stopped breathing, many resuscitation attempts were made, but all failed. After his death a tiny mark was found on his shoulder.
Actually, this animal is not too dangerous, if we are not disturbing them. It is because it not always like to attack human, but sometimes it will attack its prey when it feels been threatened or agitated since it need to be defense itself.
However, when the tides ebbed, this animal sometimes can be found mistakenly on mudflat or rocky pools- though it can live short periods of time out of water. Because of its color that looks alike rocks, people will mistakenly stepped on it make it need to defense itself, thus injecting its venom to the person.Two types of poison secreted by two separate poison glands are used against prey and predators. One of the poisons is used for hunting crab, the other, which is extremely toxic, is used as self defense against predators, perhaps human.
Figure 8 & 9: Show the government's warning signboard on the presence of the Blue-Ringed Octopus in Australia coastal.
How Its Venom Can Kill Human?
The octopus produces venom that contains tetrodotoxin, 5-hydroxytryptamine, hyaluronidase, tyramine, histamine, tryptamine, octopamine, taurine, acetylcholine and dopamine. The major neurotoxin component of Blue-Ringed Octopus venom was originally known as maculotoxin, but was later found to be identical to tetrodoxin, a neurotoxin which is also found in pufferfish and cone snails. Tetrodotoxin blocks sodium channels, causing motor paralysis and sometimes respiratory arrest, leading to cardiac arrest due to a lack of oxygen, thus cause death. The toxin is created by bacteria in the salivary glands of the octopus.
"First you will feel nauseous. Your vision becomes hazy. Within seconds you are blind. You lose your sense of touch. You cannot speak or swallow. Three minutes later you are paralyzed and unable to breath"