Southern Keeled Octopus
Southern Australia from Great Australian Bight to Tasmania and eastern Victoria (VIC, TAS, SA, WA).Features:
A moderate-sized muscular octopus with an armspan that reaches around 50 cm. The body is oval in shape and is rimmed around the sides by a raised skin ridge or keel. The arms are around 3-4 times the body length, each with two rows of suckers. The webs are deep, particularly between the side arms. The colour is generally cream to mottled orange-brown. The skin is covered in regular small low bumps and fingers of skin can be raised above the eyes and over the body.Ecology/Way of Life:
This octopus lives on sand and mud substrates in coastal waters to depths of at least 250 m. It emerges at night to forage over the sand for crabs and other crustaceans. During the day it buries in the sand or hides in shells or human refuse (such as bottles). It can raise one eye like a periscope to check if the coast is clear of predators before emerging. The common name of this octopus comes from the ridge of skin around the edge of the body, a structure also found in other octopuses that bury in the sand. It may aid in gliding the octopus under the sand when it buries. This octopus buries close to the sand surface so that it can still draw clean water in to its gill cavity in order to gain oxygen. It can do this by having the opening to the gill cavity close to the surface or by poking out the funnel and taking quick gasps of clean water.
Courtship consists of males standing on their arm tips and flaring the webs as they approach females. They quickly grab the females and use their long thin modified arm tip on the third right arm to pass sperm packages into the female's oviducts. Females lay large single eggs that are attached singly to hard surfaces such as shells or human rubbish. The young are well developed at hatching and immediately start foraging on the sea floor.Interaction with Humans/Threats:
This octopus is caught in low quantities in baitless pot fisheries in bays and inlets in South Australia and Victoria. It is sold for human consumption and as bait.Further Reading:
Stranks, T. and M.D. Norman. 1992. Review of the Octopus australis complex (Cephalopoda: Octopodidae) and description of a new species. Memoirs of the Museum of Victoria, 53(2): 345-373.
Norman, M.D. and A. Reid. 2000. A guide to the squid, cuttlefishes and octopuses of Australasia. Gould League/CSIRO Publishing, Melbourne. 96 pp.
Norman, M.D. 2000. Cephalopods: A world guide. ConchBooks, Hackenheim, Germany.
Text & map by Mark Norman; photographs by Mark Norman and Simon Foale.Sponsorship welcomed:
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