Greater blue-ringed octopus | |
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Hapalochlaena lunulata | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Cephalopoda |
Order: | Octopoda |
Family: | Octopodidae |
Genus: | Hapalochlaena Robson, 1929 |
Species: | H. lunulata |
Binomial name | |
Hapalochlaena lunulata | |
The greater blue-ringed octopus (Hapalochlaena lunulata) is one of four species of extremely venomous blue-ringed octopuses belonging to the family Octopodidae. This particular species of blue-ringed octopus is known as one of the most toxic marine animals in the world.
The greater blue-ringed octopus, despite its vernacular name, is a small octopus whose size does not exceed 10 centimetres (3.9 in), arms included, with an average weight of 80 grams (2.8 oz). Its common name comes from the relatively large size of its blue rings (7 to 8 millimetres [0.28 to 0.31 in] in diameter), which are larger than those of other members of the genus and help to distinguish this type of octopus. The head is slightly flattened dorsoventrally (front to back) and finished in a tip. Its eight arms are relatively short.
There are variable ring patterns on the mantle of Hapalochlaena lunulata with varied coloration in correlation to their ambient environment, from yellow ocher to light brown or even white-ish (when inactive). The blue rings, which number around 60, are spread throughout the entirety of its skin. The rings are roughly circular in shape and are based on a darker blotch than the background color of the skin. A black line, with thickness varying to increase contrast and visibility, borders the electric blue circles. The blue rings are an aposematic adornment to clearly show to all potential predators that the octopus is highly venomous. The octopus also has characteristic blue lines running through its eyes.
The octopus usually flashes its iridescent rings as a warning signal, each flash lasting around a third of a second. To test the theory if blue-ringed octopuses could produce their own blue iridescence, scientists bathed the octopus samples in a wide range of chemicals that were known to affect chromatophores and iridophores. It was found that none of the chemicals used affected the octopuses' ability to produce its blue rings. It was also found that after examining the blue rings (specifically the iridophores) were seen to shift to the UV end of the spectrum which is a defining characteristic of multi-layer reflectors. It was also found that the iridophores are nicely tucked into the modified skin folds, kind of like pouches, which could be contracted by the muscles that connect the center of each ring to the rim. When the muscles then relax, the muscles around the perimeter of the ring contract which in turn causes the pouch to open to expose the iridescent flash. The octopus can then expand the brown chromatophores on either side of its ring to enhance the contrast of its iridescence. After all of the testing was complete, it was determined that the muscle contracting mechanisms was key to how the blue-ringed octopus portrayed its iridescent signaling success. [2]
The greater blue-ringed octopus is a benthic animal that has a solitary way of life and is widespread throughout the tropical and subtropical waters of the Indo-West Pacific, from Sri Lanka to the Philippines and from Australia to Papua New Guinea, the Solomon Islands and Vanuatu. The animal prefers shallow waters with a mixed seabed (such as rubble, reefs and sandy areas). As is true for all octopuses, it lives in a burrow and only comes out to search for food or a mate. The entrance of the shelter is littered with remains from meals (empty shells and crab shell and legs) and is easily identifiable. [3]
The blue-ringed octopus diet typically consists of small crabs and shrimp. They also tend to take advantage of small injured fish if they can catch them. Its known hunting behavior consists of pouncing on its prey, seizing it with its arms, and then pulling it towards its mouth. It uses its horny beak to pierce through the tough crab or shrimp exoskeleton, releasing its venom. The venom paralyzes the muscles required for movement, which effectively kills the prey.
The initiation of physical contact is completely independent from sex, size, or residency status which left no notable changes of behavior based on sex alone. However, spermatophores are only released during sexual interaction with females but not with males which indicates that upon copulation, the male can distinguish the difference on whether to inseminate or not. The copulation times between male-female are roughly 160.5 minutes, while the copulation times with the male-male interactions lasted about 30 seconds. Ultimately the studies that were conducted determined that until copulation occurs, prior to insertion of the hectocotylus, the male cannot determine the difference in sex.
The breeding season varies according to geographical area. The female lays between 60 and 100 eggs, which are kept under the female's arms during the incubation period, which lasts about a month. Newborns have a brief planktonic development passage before settling on the seabed.
The mating ritual begins when a male approaches a female and begins to caress her with his modified arm, the hectocotylus. Males then climb on the female's back, at times completely engulfing the female's mantle obstructing her vision. The hectocotylus is inserted under the mantle of the female and spermatophores are released into the female's oviduct. Males die after mating. The female then lays between 50 and 100 eggs and guards them by carrying them under her arm until they hatch about 50 days later into planktonic paralarvae. The female then dies as she refuses to eat while she guards her eggs. The blue-ringed octopus is about the size of a pea when hatched then grows to reach the size of a golf ball as an adult. They mature quickly and begin mating the following autumn. Their average lifespan is about 2 years.
The greater blue-ringed octopus is capable of inflicting a deadly bite to its predators that can potentially be fatal to humans. Octopuses from genus Hapalochlaena have two kinds of venom glands that impregnate their saliva. One is used to immobilize the hunted crustaceans before eating them. The second, tetrodotoxin, is used for defense and is found in several other sea creatures such as pufferfish. Tetrodotoxin, also known as TTX, is secreted from the posterior salivary glands which is connected to the beak. The greater blue-ringed octopus is known as one of the most venomous marine animals in the entire world. For humans, the minimal lethal dose of tetrodotoxin is estimated to be about 10,000 MU, which is about 2 milligrams (0.031 gr) in crystal form. TTX does not decompose during heating or boiling and there is no known antidote or antitoxin for this toxin. It is believed that the TTX serves as a hunting tool for paralyzing prey as well as a defense mechanism to other predators. [4] This toxin is a powerful neurotoxin and a strong paralytic. The bite is painless to humans but effects appear any time between 15 and 30 minutes and up to four hours, though the rate of onset of symptoms varies by individual, and children are more sensitive to the toxins.
The first phase of the poisoning is characterized by facial and extremity paresthesia, and the victim feels tingling and/or numbness on the face, tongue, lips, and other body extremities. The victim may also suffer excessive sweating, severe headaches coupled with dizziness, speech problems, hypersalivation, moderate emesis, movement disorders, a feeling of weakness, cyanosis to extremities and lips and petechial hemorrhages on the body.
The second phase of poisoning usually occurs after eight hours and includes hypotension and generalized spastic muscle paralysis. Death may occur between 20 minutes and 24 hours after the onset of symptoms, usually resulting from respiratory paralysis. Throughout each of the phases of poisoning, the state of consciousness of the victim is unaffected. [5]
Greater Blue Ringed Octopuses express VGSC (HlNav1) gene mutations that greatly reduce the channels TTX binding affinity which in turn render the octopus TTX resistant. TTX selectively binds and blocks the ion-conducting pore of the voltage-gated sodium channel which are responsible for the ability of an organism to move. The greater blue-ringed octopus naturally produced TTX and bears a phenotype in the genus for the resistance to TTX. It was found that the resistance was caused by a combination of amino acid substitutions in the TTX binding sites for the primary voltage-gated sodium ion channel.
An octopus is a soft-bodied, eight-limbed mollusc of the order Octopoda. The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like other cephalopods, an octopus is bilaterally symmetric with two eyes and a beaked mouth at the center point of the eight limbs. The soft body can radically alter its shape, enabling octopuses to squeeze through small gaps. They trail their eight appendages behind them as they swim. The siphon is used both for respiration and for locomotion, by expelling a jet of water. Octopuses have a complex nervous system and excellent sight, and are among the most intelligent and behaviourally diverse of all invertebrates.
A cephalopod is any member of the molluscan class Cephalopoda such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot. Fishers sometimes call cephalopods "inkfish", referring to their common ability to squirt ink. The study of cephalopods is a branch of malacology known as teuthology.
Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and birds, in contrast, have a class of cells called melanocytes for coloration.
Blue-ringed octopuses, comprising the genus Hapalochlaena, are four extremely venomous species of octopus that are found in tide pools and coral reefs in the Pacific and Indian oceans, from Japan to Australia. They can be identified by their yellowish skin and characteristic blue and black rings that can change color dramatically when the animal is threatened. They eat small crustaceans, including crabs, hermit crabs, shrimp, and other small sea animals.
Tetrodotoxin (TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an order that includes pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin. Although tetrodotoxin was discovered in these fish, it is found in several other animals. It is also produced by certain infectious or symbiotic bacteria like Pseudoalteromonas, Pseudomonas, and Vibrio as well as other species found in symbiotic relationships with animals and plants.
The blue-lined octopus is one of four species of highly venomous blue-ringed octopuses. It can be found in Pacific Ocean waters that stretch from Australia to Japan. It is most commonly found around intertidal rocky shores and coastal waters to a depth of 15 metres (49 ft) between southern Queensland and southern New South Wales. It is relatively small, with a mantle up to 45 millimetres (1.8 in) in length. In its relaxed state, it is a mottled yellow-brown with dark blue or black streaks covering the whole body apart from the underside of its arms, but its vibrant blue markings appear as a warning to predators when it feels threatened. Along with its other closely related species, the blue-lined octopus is regarded as one of the most dangerous animals in the sea, and its venom can be fatal to humans. This benthic octopus is one of four members of the genus Hapalochlaena, with the other species being the greater blue-ringed octopus, southern blue-ringed octopus, and the blue-ringed octopus. The blue-lined octopus is the only species of the four to display lined iridescent blue marking, as opposed to circular iridescent blue marking that the three other species tend to exhibit.
A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores may additionally contain nourishment for the female, in which case it is called a nuptial gift, as in the instance of bush crickets. In the case of the toxic moth Utetheisa ornatrix, the spermatophore includes sperm, nutrients, and pyrrolizidine alkaloids which prevent predation because it is poisonous to most organisms. However, in some species such as the Edith's checkerspot butterfly, the "gift" provides little nutrient value. The weight of the spermatophore transferred at mating has little effect on female reproductive output.
A hectocotylus is one of the arms of male cephalopods that is specialized to store and transfer spermatophores to the female. Structurally, hectocotyli are muscular hydrostats. Depending on the species, the male may use it merely as a conduit to the female, analogously to a penis in other animals, or he may wrench it off and present it to the female.
The California two-spot octopus, often simply called a "bimac", is an octopus species native to many parts of the Pacific Ocean including the coast of California. One can identify the species by the circular blue eyespots on each side of its head. Bimacs usually live to be about two years old. They are closely related to Verrill's two-spot octopus. In 2015, the genome was sequenced.
The southern blue-ringed octopus is one of three highly venomous 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 centimetres (8 in) long and on average weighs 26 grams (0.9 oz). They are normally a docile species, but they are highly venomous, possessing venom capable of killing humans. Their blue rings appear with greater intensity when they become aggravated or threatened.
The Caribbean reef octopus is a coral reef marine animal. It has eight long arms that vary in length and diameter. In comparison to the arms, the mantle is large and bulky. This species is difficult to describe because it changes color and texture to blend into its surroundings, using specialised skin cells known as chromatophores. Its color range is very large; it can change from crimson to green, and bumpy to smooth. It weighs around 3.3 lb or 1.5 kg.
Cuttlefish, or cuttles, are marine molluscs of the order Sepiida. They belong to the class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone, which is used for control of buoyancy.
Structural coloration in animals, and a few plants, is the production of colour by microscopically structured surfaces fine enough to interfere with visible light instead of pigments, although some structural coloration occurs in combination with pigments. For example, peacock tail feathers are pigmented brown, but their microscopic structure makes them also reflect blue, turquoise, and green light, and they are often iridescent.
Abdopus aculeatus is a small octopus species in the order Octopoda. A. aculeatus has the common name of algae octopus due to its typical resting camouflage, which resembles a gastropod shell overgrown with algae. It is small in size with a mantle around the size of a small orange and arms 25 cm in length, and is adept at mimicking its surroundings.
Sepioloidea lineolata or more commonly known as the striped pyjama squid or the striped dumpling squid is a type of bottletail squid that inhabits the Indo-Pacific Oceans of Australia. Although traditionally falling within Sepiida, the cuttlefish order, it lacks a cuttlebone. More recent phylogenomic evidence suggests bottletail and bobtail squid may form their own order, Sepiolida. The striped pyjama squid lives on the seafloor and is both venomous and poisonous. When fully mature, a striped pyjama squid will only be about 7 to 8 centimetres in length. Baby striped pyjama squid can be smaller than 10 millimetres (0.39 in).
Wunderpus photogenicus, the wunderpus octopus, is a small-bodied species of octopus with distinct white and rusty brown coloration. 'Wunderpus' from German “wunder” meaning ‘marvel or wonder’.
Abdopus capricornicus is a species of octopus in the family Octopodidae, and is often also referred to as Octopus capricornicus. This octopus is native to the Great Barrier Reef and is often found throughout the Indo-West Pacific Ocean. There are six other species of octopuses within the subgenus Abdopus with a large number of organisms not yet described. This octopus is notable for its unique body patterning through which it can change. The likely uses for this characteristic are camouflage or intraspecific communication. Other organisms in the Abdopus genus include A. horridus, A. abaculus, A. aculeatus, and A. tonganus. Individuals are capable of autotomy, sacrificing a writhing arm to a predator to distract it while making an escape.
Octopus bocki is a species of octopus, which has been located near south Pacific islands such as Fiji, the Philippines, and Moorea and can be found hiding in coral rubble. They can also be referred to as the Bock's pygmy octopus. They are nocturnal and use camouflage as their primary defense against predators as well as to ambush their prey. Their typical prey are crustaceans, crabs, shrimp, and small fish and they can grow to be up to 10cm in size.