Hapalochlaena lunulata

Description: The blue-ringed octupuses are of the genus Hapalochlaena. There are three or four species of octopus that live in tide pools in the Pacific Ocean, in the Southeast Asia and Australia region. They are currently recognized as one of the world's most venomous marine animals. Despite being quite small and usually calm in nature, they can prove to be quite dangerous to humans. They can be identified by their characteristic blue and black rings and yellowish skin. When the octopus is agitated, the brown patches darken, and iridescent blue rings or clumps of rings appear and pulsate within the maculae. Typically, 50 to 60 blue rings cover the dorsal and lateral surfaces of the mantle.
Niche: They hunt small crabs, hermit crabs, and shrimp. They may bite attackers, including humans, if provoked.

Habitat: The ocean
Unusually: Individual blue-ringed octopus tends to use its skins' chromatophore cells to camouflage itself until provoked, at which point it quickly changes colour, becoming bright yellow with blue rings or lines.
Provisions: Their diet normally consists of small crab and shrimp. However, they may also feed on fish if they can catch them. They pounce on their prey, paralyze them with venom and use their beaks to tear off pieces. They then suck out the flesh from the crustacean's exoskeleton.


The mating ritual for the blue-ringed octopus begins when a male approaches a female and attempts to caress her with his hectocotylus, or modified arm. The male grabs the female by grabbing her mantle, which sometimes interferes with the female's vision, then transferring sperm packets. He does this by inserting his hectocotylus into her mantle cavity repeatedly. Males will attempt intercourse with members of their own species without regards to sex or size. Interactions between males are most often shorter in duration, however, and end with the mounting octopus withdrawing the hectocotylus without sperm packet insertion or struggle.
Blue-ringed octopus females lay only one clutch of about fifty eggs in their lifetime towards the end of autumn. Eggs are laid, then incubated underneath the female's arms for approximately six months. During this process she does not eat. After the eggs hatch, the female dies, and the new offspring will grow, reach maturity, and be able to mate by the next year.


The blue-ringed octopus is not very large, 12 to 20 cm (approx. 5 to 8 inches), but its venom is powerful enough to kill humans. There is no anti-venom available for blue-ringed octopuses.
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. It is 10,000 times more toxic than cyanide.Tetrodotoxin blocks sodium channels, which can cause motor paralysis, respiratory arrest, and cardiac arrest due to a lack of oxygen. The toxin is produced by bacteria in the octopus's salivary glands.


First aid treatment for the venom requires pressure on the wound and artificial respiration once the paralysis has disabled the victim's respiratory muscles, which often happens minutes after being bitten. Tetrodotoxin causes severe and often total body paralysis. The victim remains conscious and alert. This effect is temporary and will fade over a period of hours as the tetrodotoxin is metabolized and excreted by the body. It is essential that rescue breathing be continued without pause until the paralysis subsides and the victim regains the ability to breathe on their own. Using a bag valve mask respirator reduces fatigue to sustainable levels until an ambulance can arrive.
Professional hospital treatment involves placing the patient on a ventilator until the toxin is neutralized by the body. The symptoms vary in severity; children tend to be high-risk due to their smaller body size. Due to the venom primarily killing through paralysis, victims are frequently saved if artificial respiration is started and maintained before cyanosis and hypotension develop. Victims who live through the first 24 hours generally fully recover.

Structure of an Octopus
Structure of an Octopus

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