The blue-lined octopus (''Hapalochlaena fasciata'') is one of four
species of highly
venomous blue-ringed octopuses. It can be found in Pacific Ocean waters that stretch from
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
to
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
.
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.
Behavior
Blue-lined octopuses tend to swim around shallow areas of
coral reefs and
tide pools.
They often hide in crevices of reefs, empty seashells, and other ocean resources they can find to conceal their identity.
They are
diurnal creatures, hunting
crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...
s and small
fish during the day.
They do not use their venom (known as
tetrodotoxin) to kill their prey, but instead trap it inside their arms and pierce them with its parrot-like beak.
Lethality
Blue-lined octopuses can be very lethal to humans. Their saliva contain a special
neurotoxin
Neurotoxins are toxins that are destructive to nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insultsSpencer 2000 that can adversely affect function in both developing and mature ner ...
called
tetrodotoxin.
However, the species is more likely to flee and find shelter in an encounter due to their extremely shy nature.
Nonetheless, there have been at least three reported human deaths from the blue-lined octopus.
It poses most danger to those who pick up the octopus and physically touch it.
If a human is to be attacked by the octopus, the injection may not be felt at first due to the small injection apparatus of the octopus.
After some time, symptoms of the injection include loss of feeling in the tongue/lips,
muscle weakness
Muscle weakness is a lack of muscle strength. Its causes are many and can be divided into conditions that have either true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, includi ...
/
paralyzation,
respiratory failure,
unconsciousness, and eventually
death.
The tetrodotoxin in blue-lined octopuses is so lethal that it has been estimated that the venom from a single 25-gram octopus can kill about ten 75-kilogram humans.
Reproduction
The blue-lined octopuses start
reproducing at a year old.
Males seek out female companions and then pounce on them. If they are successful, the female octopus will lay 50 to 100
eggs 30 days after the encounter.
During the 30 days, the female octopus hides her eggs under her arms and does not leave her hiding spot until the eggs hatch.
After laying her eggs, the female octopus dies.
References
{{Taxonbar, from=Q2120872
Octopuses