Species of the month: Southern Blue-Ringed Octopus

Rose and Jess’ exciting find of a Southern Blue-Ringed Octopus (Hapalochlaena maculosa) at Cape Douglas with families from the local home-school network is our Species of the Month for April. (For those that are interested, the Limestone Coast Homeschool Group contact is Nicole: .)

There are actually four species collectively known as Blue-Ringed Octopuses (and yes, octopuses is an accepted plural!), but in this article we are just referring to the species found in south-eastern Australia. The Southern Blue-Ringed Octopus is a small, short-lived octopus known for its fluorescent blue rings.

They grow to a maximum of 12 cm long, and live on reefs, sandy rubble and in seagrass on sheltered to moderately exposed coasts in South Australia, Victoria and northern Tasmania. They hide under rocks, in empty shells, as well as in discarded bottles and cans. During the day the Blue-Ringed Octopus hides, coming out at night to feed on crabs and shrimps. Despite the colours for which it is known, Blue-Ringed Octopuses camouflage well among rocks and shells as it is only when irritated or alarmed their blue rings flash in warning.

A camouflaged Southern Blue-ringed Octopus at Cape Douglas (in the centre of the photo). Photo: Rose Thompson

These intriguing octopuses only live for 12-18 months. In late autumn, females lay about 50 eggs which they carry around under their arms for six months! Her life comes to a natural end once the once the eggs have hatched. The young hatch looking like miniature adults, growing quickly to maturity and mate in early autumn. After mating the male dies and the female looks after the eggs.

Blue-Ringed Octopuses are known for their powerful nerve toxin that is injected with saliva to paralyse it’s prey. Bites to humans are reasonably rare, but they can be fatal – so it’s important not to touch these creatures! They are extremely timid and only bite humans in self-defence if handled.

Here is quick snippet of video that Rose captured.

References:

Edgar, G.J. (2000). Australian marine life: the plants and animals of temperate waters, Reed New Holland, Frenchs Forest, N.S.W.; London.

Gowlett-Holmes, K.L. (2008). A field guide to the marine invertebrates of South Australia, Notomares, Sandy Bay, Tas., Australia.

Jess Bourchier


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