bitch-dont-krill-my-vibe: Rock Pool Adventures: Part 5 – Gloomy…


Rock Pool Adventures: Part 5 – Gloomy Octopus

Common Sydney Octopus (Octopus tetricus)
This cryptic species can be found in temperate rock pools and sub-tidal waters along Australia’s East coast. However, its range is shifting poleward due to climate change. They feed on crustaceans and molluscs, and have a short lifespan of about 11 months. Their body (mantle) grows up to 80 cm, while their arms grow up to 2 m. 

Fun Fact:
They are able to mimic the appearance of seaweed through changing their colouration and body texture.

Why is it nick-named the ‘gloomy’ octopus?
This is largely due to its dark grey exterior, and its tendency to be territorial and solitary. During the day they remain in their lair – which is decorated with the shells of its prey. Despite this, gloomy octopuses have been observed co-existing with each other – particularly in areas with high abundance. Perhaps they’re not so gloomy after all.

About this series: Its winter in Australia, which means I’m switching snorkelling for rock pool exploring! Armed with dive boots, dive gloves, and a cheap iPhone macro-lens attachment, I have set off to search the coastline!

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Pictures, from top to bottom: 1) Octopus tetricus in rock pool, next to M. calcar starfish. 2-4) Gifs of Octopus tetricus interacting with some string.
Photos taken at Bilgola Beach, NSW (2017), by Andrea Henning and Haley Henning.

[1] Norman, M. and Reid, A., 2000. Guide to squid, cuttlefish and octopuses of Australasia. CSIRO publishing.

[2] Godfrey-Smith, P. and Lawrence, M., 2012. Long-term high-density occupation of a site by Octopus tetricus and possible site modification due to foraging behavior. Marine and freshwater behaviour and physiology, pp.1-8.

[3] Ramos, J.E., Pecl, G.T., Moltschaniwskyj, N.A., Strugnell, J.M., León, R.I. and Semmens, J.M., 2014. Body size, growth and life span: implications for the polewards range shift of Octopus tetricus in south-eastern Australia. PloS one, 9(8), p.e103480.