Blue-ringed octopus

Blue-ringed octopus

Overview
The blue-ringed octopuses (genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Hapalochlaena) are three (or perhaps four) octopus
Octopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...

 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 that live in tide pools in the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, from Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 to Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 (mainly around southern New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

 and South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...

). They are currently recognized as one of the world's most venom
Venom
Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...

ous marine animals. Despite their small size and relatively docile nature, they can prove a danger to humans. They can be recognized by their characteristic blue and black rings and yellowish skin.
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Encyclopedia
The blue-ringed octopuses (genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Hapalochlaena) are three (or perhaps four) octopus
Octopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...

 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 that live in tide pools in the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, from Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 to Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 (mainly around southern New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

 and South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...

). They are currently recognized as one of the world's most venom
Venom
Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...

ous marine animals. Despite their small size and relatively docile nature, they can prove a danger to humans. They can be recognized by their characteristic blue and black rings and yellowish skin. When the octopus is agitated, the brown patches darken dramatically, and iridescent blue rings or clumps of rings appear and pulsate within the maculae. Typically 50-60 blue rings cover the dorsal and lateral surfaces of the mantle. They hunt small crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...

s, hermit crabs, and shrimp, and may bite attackers, including humans, if provoked.

Classification


The genus was described by British zoologist Guy Coburn Robson
Guy Coburn Robson
Guy Coburn Robson was a British zoologist, specializing in Mollusca, who first named and described Mesonychoteuthis hamiltoni, the Colossal Squid....

 in 1929. There are three confirmed species of Hapalochlaena, and a fourth is still being researched:
  • Greater Blue-ringed Octopus
    Greater Blue-ringed Octopus
    The Greater Blue-ringed Octopus is one of three species of blue-ringed octopuses. Unlike its southern brethren, the Blue-lined and Southern Blue-ringed octopuses that are found only in Australian waters, the range of the Greater Blue-ringed Octopus spans the tropical western Pacific Ocean...

     (Hapalochlaena lunulata)
  • Southern Blue-ringed Octopus
    Southern Blue-ringed Octopus
    The Southern Blue-ringed Octopus is one of 3 species of blue-ringed octopuses. It is most commonly found in tidal rock pools along the south coast of Australia. As an adult, it can grow up to 20 centimeters long and on average weighs 26 grams...

     or Lesser Blue-ringed Octopus (Hapalochlaena maculosa)
  • Blue-lined Octopus
    Blue-lined Octopus
    The Blue-lined Octopus is one of 3 species of Blue-ringed octopuses. It is most commonly found around intertidal rocky shores and coastal waters to a depth of between southern Queensland and southern New South Wales. Its mantle length can grow up to 45 mm...

     (Hapalochlaena fasciata)
  • Hapalochlaena nierstraszi - described in 1938 from a single specimen from the Bay of Bengal
    Bay of Bengal
    The Bay of Bengal , the largest bay in the world, forms the northeastern part of the Indian Ocean. It resembles a triangle in shape, and is bordered mostly by the Eastern Coast of India, southern coast of Bangladesh and Sri Lanka to the west and Burma and the Andaman and Nicobar Islands to the...

    ; the validity of this taxon has been questioned.

Behaviour


An individual blue-ringed octopus tends to use its dermal chromatophore
Chromatophore
Chromatophores are pigment-containing and light-reflecting cells found in amphibians, fish, reptiles, crustaceans, and cephalopods. They are largely responsible for generating skin and eye colour in cold-blooded animals and are generated in the neural crest during embryonic development...

 cells to camouflage itself until provoked, at which point it quickly changes colour, becoming bright yellow with blue rings or lines.

Feeding


Their diet typically consists of small crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...

 and shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...

, but 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
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

's exoskeleton
Exoskeleton
An exoskeleton is the external skeleton that supports and protects an animal's body, in contrast to the internal skeleton of, for example, a human. In popular usage, some of the larger kinds of exoskeletons are known as "shells". Examples of exoskeleton animals include insects such as grasshoppers...

.

Reproduction


The mating ritual for the blue-ringed octopus begins when a male approaches a female and begins to caress her with his modified arm, the hectocotylus
Hectocotylus
A hectocotylus is one of the arms of the male of most kinds of cephalopods that is modified in various ways to effect the fertilization of the female's eggs. It is a specialized, extended muscular hydrostat used to store spermatophores, the male gametophore...

. A male mates with a female by grabbing her mantle
Mantle (mollusc)
The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...

, which sometimes completely obscures the female's vision, then transferring sperm
Sperm
The term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell...

 packets by inserting his hectocotylus
Hectocotylus
A hectocotylus is one of the arms of the male of most kinds of cephalopods that is modified in various ways to effect the fertilization of the female's eggs. It is a specialized, extended muscular hydrostat used to store spermatophores, the male gametophore...

 into her mantle cavity repeatedly. Mating continues until the female has had enough, and in at least one species the female has to remove the over-enthusiastic male by force. Males will attempt copulation with members of their own species regardless of sex or size, however interactions between males are most often shorter in duration and end with the mounting octopus withdrawing the hectocotylus without 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, and during this process she does not eat. After the eggs hatch, the female dies, and the new offspring will reach maturity and be able to mate by the next year.

Venom



The blue-ringed octopus is 12 to 20 cm (5 to 8 inches), but its venom is powerful enough to kill humans. There is no blue-ringed octopus antivenom available.

The octopus produces venom that contains tetrodotoxin
Tetrodotoxin
Tetrodotoxin, also known as "tetrodox" and frequently abbreviated as TTX, sometimes colloquially referred to as "zombie powder" by those who practice Vodou, is a potent neurotoxin with no known antidote. There have been successful tests of a possible antidote in mice, but further tests must be...

, 5-hydroxytryptamine, hyaluronidase
Hyaluronidase
The hyaluronidases are a family of enzymes that degrade hyaluronic acid.In humans, there are six associated genes, including HYAL1, HYAL2, HYAL3, and PH-20/SPAM1.-Use as a drug:...

, tyramine
Tyramine
Tyramine is a naturally occurring monoamine compound and trace amine derived from the amino acid tyrosine. Tyramine acts as a catecholamine releasing agent...

, histamine
Histamine
Histamine is an organic nitrogen compound involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by...

, tryptamine
Tryptamine
Tryptamine is a monoamine alkaloid found in plants, fungi, and animals. It is based around the indole ring structure, and is chemically related to the amino acid tryptophan, from which its name is derived...

, octopamine
Octopamine
Octopamine is an endogenous biogenic amine that is closely related to norepinephrine, and has effects on the adrenergic and dopaminergic systems. It is also found naturally in numerous plants, including bitter orange. Biosynthesis of the D--enantiomer of octopamine is by β-hydroxylation of...

, taurine, acetylcholine
Acetylcholine
The chemical compound acetylcholine is a neurotransmitter in both the peripheral nervous system and central nervous system in many organisms including humans...

, and dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...

. The major neurotoxin component of blue-ringed octopus venom was originally known as maculotoxin but was later found to be identical to tetrodotoxin
Tetrodotoxin
Tetrodotoxin, also known as "tetrodox" and frequently abbreviated as TTX, sometimes colloquially referred to as "zombie powder" by those who practice Vodou, is a potent neurotoxin with no known antidote. There have been successful tests of a possible antidote in mice, but further tests must be...

, a neurotoxin which is also found in pufferfish
Pufferfish
Tetraodontidae is a family of primarily marine and estuarine fish of the Tetraodontiformes order. The family includes many familiar species which are variously called pufferfish, balloonfish, blowfish, bubblefish, globefish, swellfish, toadfish, toadies, honey toads, sugar toads, and sea squab...

 and cone snail
Cone snail
Conidae is a taxonomic family of minute to quite large sea snails, marine gastropod molluscs in the superfamily Conoidea.The snails within this family are sophisticated predatory animals...

s that is 10,000 times more toxic than cyanide
Cyanide
A cyanide is a chemical compound that contains the cyano group, -C≡N, which consists of a carbon atom triple-bonded to a nitrogen atom. Cyanides most commonly refer to salts of the anion CN−. Most cyanides are highly toxic....

. Tetrodotoxin blocks sodium channels, causing motor
Motor system
The motor system is the part of the central nervous system that is involved with movement. It consists of the pyramidal and extrapyramidal system....

 paralysis
Paralysis
Paralysis is loss of muscle function for one or more muscles. Paralysis can be accompanied by a loss of feeling in the affected area if there is sensory damage as well as motor. A study conducted by the Christopher & Dana Reeve Foundation, suggests that about 1 in 50 people have been diagnosed...

 and respiratory arrest
Respiratory arrest
Respiratory arrest is the cessation of breathing. It is a medical emergency and it usually is related to or coincides with a cardiac arrest. Causes include opiate overdose, head injury, anaesthesia, tetanus, or drowning...

 within minutes of exposure, leading to cardiac arrest
Cardiac arrest
Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...

 due to a lack of oxygen. The toxin is produced by bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 in the salivary glands of the octopus.

Treatment


First aid
First aid
First aid is the provision of initial care for an illness or injury. It is usually performed by non-expert, but trained personnel to a sick or injured person until definitive medical treatment can be accessed. Certain self-limiting illnesses or minor injuries may not require further medical care...

 treatment is pressure on the wound and artificial respiration
Artificial respiration
Artificial respiration is the act of assisting or stimulating respiration, a metabolic process referring to the overall exchange of gases in the body by pulmonary ventilation, external respiration, and internal respiration...

 once the paralysis has disabled the victim's respiratory muscles, which often occurs within minutes of being bitten. Tetrodotoxin causes severe and often total body paralysis; the victim remains conscious and alert in a manner similar to curare
Curare
Curare is a common name for various arrow poisons originating from South America. The three main types of curare are:* tubocurare...

 or pancuronium bromide. This effect, however, is temporary and will fade over a period of hours as the tetrodotoxin is metabolized and excreted by the body. It is thus essential that rescue breathing be continued without pause until the paralysis subsides and the victim regains the ability to breathe on their own. This is a daunting physical prospect for a single individual, but use of a bag valve mask
Bag valve mask
A bag valve mask is a hand-held device used to provide positive pressure ventilation to a patient who is not breathing or who is breathing inadequately. The device is a normal part of a resuscitation kit for trained professionals, such as ambulance crew...

 respirator reduces fatigue to sustainable levels until help can arrive.

Definitive hospital
Hospital
A hospital is a health care institution providing patient treatment by specialized staff and equipment. Hospitals often, but not always, provide for inpatient care or longer-term patient stays....

 treatment involves placing the patient on a medical ventilator
Medical ventilator
A medical ventilator can be defined as any machine designed to mechanically move breatheable air into and out of the lungs, to provide the mechanism of breathing for a patient who is physically unable to breathe, or breathing insufficiently....

 until the toxin is neutralized by the body. The symptoms vary in severity, with children being the most at risk because of their small body size. Because the venom primarily kills through paralysis, victims are frequently saved if artificial respiration
Artificial respiration
Artificial respiration is the act of assisting or stimulating respiration, a metabolic process referring to the overall exchange of gases in the body by pulmonary ventilation, external respiration, and internal respiration...

 is started and maintained before marked cyanosis
Cyanosis
Cyanosis is the appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface being low on oxygen. The onset of cyanosis is 2.5 g/dL of deoxyhemoglobin. The bluish color is more readily apparent in those with high hemoglobin counts than it is...

 and hypotension
Hypotension
In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...

 develop. Victims who live through the first 24 hours generally go on to make a complete recovery.

It is essential that efforts continue even if the victim appears not to be responding. Tetrodotoxin poisoning can result in the victim being fully aware of his surroundings but unable to breathe. Because of the paralysis that occurs they have no way of signaling for help or any way of indicating distress. Respiratory support, together with reassurance, until medical assistance arrives ensures that the victim will generally recover well.

The blue-ringed octopus, despite its small size, carries enough venom to kill 26 adult humans within minutes. Furthermore, their bites are tiny and often painless, with many victims not realizing they have been envenomated
Envenomation
Envenomation is the process by which venom is injected into some animal by the bite of a venomous animal. Many kinds of animals, including mammals , reptiles , spiders , insects , employ venom for hunting and for self defense...

 until respiratory depression and paralysis
Paralysis
Paralysis is loss of muscle function for one or more muscles. Paralysis can be accompanied by a loss of feeling in the affected area if there is sensory damage as well as motor. A study conducted by the Christopher & Dana Reeve Foundation, suggests that about 1 in 50 people have been diagnosed...

start to set in.

External links