Known from deep waters off the south-east coast of Australia, from the Great Australian Bight to New South Wales and Tasmania (NSW, VIC, TAS, SA, WA).Features:
A soft-bodied deep-sea octopus that reaches at least 30 cm in length. There are a pair of small fins towards the rear of the body. The body is squat to square and the eyes are large. There are eight arms joined by deep webs that reach the arm tips. Each arm has a single row of suckers flanked on either side by a row of finger-like projections known as cirri. The shell consists of a cartilage U-shaped structure. The opening to the gill cavity is very narrow, fitting tightly around the funnel. The animal is grey to pink-red in colour and the skin is smooth.Ecology/Way of Life:
This deep-sea octopus has been collected at depths between 400 and 700 metres in deep-water trawls, typically found close to the sea floor. As for other members of this group, swimming takes three forms: swimming using the fins with the arms trailing along behind; gliding as a wide flat pancake using the fins and jet propulsion (the source of the common name); or regular opening and closing of the arms and webs like the beating bell of a jellyfish. The sensory fingers along the arms (cirri) are thought to be used to sense prey, either sensing chemical cues or vibrations in the water.
Adult males have enlarged suckers but lack the arm modifications that are found in other octopuses. The penis is well developed and may be used to directly insert sperm packages into the female's single oviduct. Females lay large eggs encased in a horny outer coating. They are probably attached singly to the seafloor and left to develop on their own.
The finned deep-sea octopuses are a fascinating but poorly known group. Some species have been recorded to depths of over seven kilometres. Little is known of their behaviour and biology.Interaction with Humans/Threats:
The deep-water existence of this unusual creature means that there is little overlap with human activities.Further Reading:
Norman, M.D. 2000. Cephalopods: A world guide. ConchBooks, Hackenheim, Germany.
Text & map by Mark Norman; illustrations by K Hollis.Sponsorship welcomed:
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