Key points
- We still have much to learn about what lives in the oceans around Australia, especially the extraordinary life found in the deep ocean.
- A world-first biodiversity survey of marine parks off Western Australia by CSIRO research vessel (RV) Investigator has led to the discovery of a new species.
- Following meticulous work by teams of experts, we welcome the newest type of 'dumbo' octopus into the described world.
The story of the Carnarvon Flapjack Octopus begins in 2022, on a science ship on the surface of the Indian Ocean.
CSIRO research vessel (RV) Investigator, having departed Fremantle in November, was carrying a team of 32 researchers on a mission to deliver a world-first biodiversity survey of the Gascoyne and Carnarvon Canyon Marine Parks off Western Australia.
What they would discover, more than 1000 metres beneath the waves, would be as intriguing as it was important.
Meet the voyage team
Led by CSIRO under Chief Scientist, Dr John Keesing, the collaborative voyage included experts in vertebrate and invertebrate marine species hailing from research organisations, collections and museums from across Australia.
“More than 70 per cent of Australia’s vast marine estate is greater than 1000 metres deep but these areas are poorly studied and we know very little about the life down there,” John said.
During their 30 days at sea, the voyage team delivered more than 180 science operations, investigating ocean life at depths from 50 to 5000 metres. They deployed special underwater cameras to film life on the seafloor, and nets and sleds to collect specimens for population, biological and further study.
The voyage represented the culmination of more than two years’ careful planning in conjunction with Parks Australia, who manage Australia’s extensive network of marine parks.
The mix of survey and sampling methods selected was vital for a comprehensive study of the biodiversity in the region and tailored to suit the habitats the researchers would encounter. Importantly, while there are various ways we can study life in the ocean, it is only through the collection of physical specimens that new species can be identified and described.
Being a world-first biodiversity survey in this region, John and the voyage team expected to collect many species that would be new to science.
Meet the curators
The specimens collected from the program of physical surveys were sorted, categorised and given a unique barcode. Each specimen was then carefully arranged and photographed, and a provisional identification was made.
In some cases, there were specimens that had the onboard experts stumped. These would be flagged for further study.
Several deep-sea octopus specimens fell into this category.
Included in the onboard expertise was a team from the Western Australian Museum (WA Museum) led by their Head of Aquatic Zoology, Dr Lisa Kirkendale.
“The Indian Ocean is truly a frontier for marine biodiversity research and the WA Museum is the region’s institutional hub as we move forward to address this challenge,” Lisa said.
Lisa and her team carefully guided the curation (preparation and preservation) of the mystery octopus specimens, along with countless other marine creatures, from carnivorous bivalves to bejewelled deep-sea squid. These would be sent back to the WA Museum for further research and to be included in their marine species collections.
Meet the octopus expert
Specimens of the unknown octopuses then waited patiently on the shelf until December 2023 when Dr Tristan Verhoeff received them on loan from the WA Museum.
Tristan, a volunteer Systematic Taxonomist at the Tasmanian Museum and Art Gallery (TMAG), had been working on a review of Australia’s cirrate octopuses since 2021.
"Cirrate octopuses are so called because they have special hairs next to their suckers called cirri," Tristan said.
"They’re also called ‘dumbo’ octopuses as the fins on their body, which is called a mantle, look like little elephant ears," he said.
Tristan carefully studied the specimens and, after identifying there was an unknown octopus in their midst, he set to work painstakingly describing the new species.
However, his discoveries didn’t finish there! Tristan also helped describe a second new species of dumbo octopus (Cirroteuthis kirrilyae) at the same time. This description was made from specimens collected on the same 2022 voyage as well as the 2017 Sampling the Abyss voyage by RV Investigator off eastern Australia.
“The process of describing these species took approximately a year, and included careful collection of measurements, sucker counts, dissection of internal organ systems, and detailed photography work,” Tristan said.
“A lot of time was also spent looking at comparative material, and going through old literature," he said.
"You also get to name the species which is fun."
Meet the octopus
On 12 May 2025, the Carnarvon Flapjack Octopus was introduced to the world by the Australian Journal of Taxonomy, in a research paper authored by Tristan. The discovery of this rare and unusual species was quickly picked up and shared by world media.
Tristan named the new species Opisthoteuthis carnarvonensis, the Carnarvon Flapjack Octopus, after the location where it was collected.
In Latin, ‘ensis’ means ‘from’ so its Latin name translates to 'from Carnarvon'.
“The species is small, the body length being up to 40 mm and a total length of up to 190 mm, and it has an orange-brown colouration,” Tristan said.
“They have fins on their body and a unique cartilaginous shell that anchors the muscles to these fins. These octopuses have an extensive web between the arms, and the jellyfish-like movement of this webbing, as well as flapping the fins, are used for propulsion, rather than the jet-propulsion used by ‘normal’ octopus,” he said.
“However, flapjack octopus are mostly benthic, resting on the seafloor.”
Interestingly, unlike other octopuses, flapjack octopuses produce no ink and cannot change colour.
The Carnarvon Flapjack Octopus is only found off north-western Australia from depths of 1000-1500 metres. Its presence adds extra value to the recently established marine parks managed by Parks Australia and its discovery will now help marine managers protect the species.
The same paper describing the Carnarvon Flapjack Octopus also revealed that north-western Australia had two other flapjack octopus species, Opisthoteuthis cf. philipii and Insigniteuthis extensa, previously unknown in Australian waters.
Tristan said many people may not be aware that museums like WA Museum and TMAG have extensive and valuable collections of deep-sea life that are available for study.
“Many of the new species I have described have been in these collections for decades awaiting someone to notice them.”