PORT PHILLIP BAY


Maori Octopus 

Octopus maorum Hutton, 1880

View scientific description and taxonomy

Scientific Details

Eight circumoral appendages; eight arms, ventrolateral tentacles absent. Mantle cavity with one opening to exterior. Arms with numerous suckers, without horny, toothed rims. Fins absent. Dorsal border of mantle fused with head. Large muscular species. Arms long, to 5.5 times mantle length. Dorsal arms longest and thickest (1>2>3>4). Webs of moderate depth, deepest around 20% of arm length. Web deepest on dorsal arms, shallowest between ventral arms. Web margins wide and fleshy extending to the arm tips. Suckers biserial; enlarged suckers present in mature males and females, around 6 on all arms, starting around the 15th proximal sucker. Gills with 13 to 15 lamellae per demibranch. Funnel organ W-shaped, outer limbs approximately 75% length of medial limbs. Funnel locking apparatus absent. Ink sac present. Right third arm of males hectocotylized, length 60-80% of opposite arm. Ligula small and narrow, around 5% of arm length. Calamus of moderate size and pointed, around 25% of ligula length. Hectocotylized arm with 95-135 suckers. Eggs of moderate size, around 6-7 mm. Colour orange brown to dark brick red with numerous small white spots scattered over mantle and dorsal arm crown. Arm faces orange. Skin texture of small irregular patches and papillae over all dorsal and lateral surfaces. More than 20 large spike-like papillae can be raised on the body and upper arm crown. Skin ridge around lateral margin of mantle absent.
Mantle length to 300 mm, total length to around 1 m, weight to around 10 kg.

Taxonomy

Phylum:
Mollusca
Class:
Cephalopoda
Subclass:
Coleoidea
Order:
Octopoda
Suborder:
Incirrata
Family:
Octopodidae
Genus:
Octopus
Species:
maorum

General Description

Large muscular octopus (Australia's largest). Body oval-shaped, eyes large. Arms long and muscular, the front pair being the longest and broadest. Colour dark orange-brown scattered with numerous small white spots. Skin covered in scattered large, unbranched fingers of skin (papillae) forming a spiky appearance in some postures. Maximum mantle length 30 cm, total length to around 1 m, weight to around 10 kg.

Biology

This octopus forms lairs in crevices or burrows, recognised by the scatter of shells and crab parts around the entrance. Larger animals often sit within the mouth of the lair. Smaller animals are generally night active while larger animals can be active during both the day and night. This octopus feeds on a wide range of prey including crabs, abalone, crayfish, mussels, fish and other octopuses. The deep webs can be flared to trap prey. Day-foraging animals are often accompanied by wrasses that grab any prey that escape the octopus' clutches. Mating occurs by the male engulfing the female within his webs and inserting the modified third right arm into her gill cavity to place sperm packets in her oviducts. The females lay strings of small eggs, attaching them to hard surfaces such as in rock crevices. The young hatch as planktonic young that travel in ocean currents between Australia and New Zealand. This octopus is harvested in both targeted fisheries and as bycatch. It is used for human consumption (often pickled in the Greek style) and as bait. This species takes a heavy toll on lobster pot fisheries throughout its range, leaving the empty lobster shells in the pots. Some estimates suggest up to one third of the potential catch is lost to octopuses.

Habitat

Rocky reefs, seaweed and seagrass meadows from the intertidal to a depth of at least 549 m.

Reefs

Seagrass meadows

Distribution guide

New Zealand and southern Australia.

Species Group

Octopuses and allies Octopuses

Depth

Shore (0-1 m)
Shallow (1-30 m)
Deep ( > 30 m)

Water Column

On or near sea floor

Max Size

1 m

Diet

Carnivore

Harmful

Potential to bite, especially if handled. Venom status unknown.

Commercial Species

No

Global Dispersal

Native to Australia

Identify

Conservation Status

  • DSE Advisory List : Not listed
  • EPBC Act 1999 : Not listed
  • IUCN Red List : Not listed

Author

article author Finn, J.K.

Dr. Julian Finn is a Senior Curator of marine invertebrates at Museum Victoria.

Author

article author Norman, M.

Dr. Mark Norman is Head of Sciences at Museum Victoria.

citation

Cite this page as:
Finn, J.K. & Norman, M., 2011, Maori Octopus, Octopus maorum, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 23 Oct 2017, http://portphillipmarinelife.net.au:8098/species/7834

Text: creative commons cc by licence