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Octopus; Blue Ringed

Octopus; Blue Ringed

Hapalochlaena maculosa

The southern blue-ringed octopus is the most common of at least 10 species of blue-ringed octopus, the most deadly genus of all cephalopods.  The common name is derived from the characteristic small (2mm), neon blue rings that appear on the upper body and arms when the animal is disturbed.  At rest the background colour is a uniform beige to grey with large brown patches, the body surface has a rough, wrinkled appearance.  The southern blue-ringed octopus is not known to be aggressive, however if provoked, they can produce an extremely toxic neuromuscular venom similar to tetrodotoxin (found in pufferfish and cone shells), created by bacteria in its salivary gland which paralyses muscles.  Another less venomous poison, secreted by a separate gland, is injected into prey, crustaceans and fish, when bitten by their beak-like mouthparts.  Several human fatalities have been attributed to bites from these small octopuses, as there is currently no antivenom and the only treatment is ongoing heart massage and artificial respiration until the poison dissipates (usually in 24 hours).  Unlike other octopuses, the blue-ringed octopus lack an ink sac.

As with most octopuses, squid and cuttlefish courtship is an important part of the mating ritual.  The male approaches the female and caresses her with his modified arm (the hectocotylus), before climbing on her back and inserting this arm under her mantle to deposit a package of sperm (the spermatophore) into the female’s oviduct.  The female  then lays 50 to 100 eggs in late autumn, which she guards under her tentacles for about 50 days, before the eggs hatch into planktonic paralarvae approximately one centimetre in length.  The female dies shortly after, having consumed no food during that time.  The young rapidly grow to maturity and mate in early autumn.  The males die after mating, and the female carries on with the eggs.  They have a short lifespan of about 2 years.  The southern blue-ringed octopus occupies tidal rock pools, sheltered and moderately exposed reef and sand often remaining hidden amongst debris on the sea floor during the day, before venturing out to feed at night.  They occur from 0 to 50 metres depth.  This species can be found in the temperate waters from southern WA to southern Queensland and around Tasmania, and grows to the small size of 15 centimetres in length.

Other common names include:  Lesser blue-ringed octopus, blue-ringed octopus

Occurrence at the Busselton Jetty: 

They are common around the jetty, but are rarely seen as they hide during the day in seagrass, in small shells and under rubble, only venturing out at night to feed.  They have been observed on numerous occasions by unsuspecting staff cleaning the windows, whom have grasped the window bracket only to find it being inhabited.