Giant squid discovery uncovers a hidden deep-sea world off Australia

The discovery comes from a Curtin University-led study that explored the Cape Range and Cloates submarine canyons, located about 1200 kilometers north of Perth. During the expedition, led by the Western Australian Museum aboard the Schmidt Ocean Institute's research vessel R/V Falkor, researchers collected more than 1,000 samples from depths reaching 4510 meters.

Instead of relying only on cameras or captured animals, the team used environmental DNA (eDNA), which consists of genetic traces naturally released by marine animals into seawater. By analyzing these tiny fragments of DNA, scientists were able to identify species living in the deep ocean without directly observing them.

Giant Squid and Rare Deep-Sea Species Detected

Among the most notable findings was evidence of the giant squid (Architeuthis dux), detected in six separate samples collected from both submarine canyons. Researchers also identified deep-diving whale species, including the Pygmy sperm whale (Kogia breviceps) and Cuvier's beaked whale (Ziphius cavirostris).

Giant squid are among the ocean's most mysterious animals. They can grow longer than a school bus (10 to 13 meters), weigh between 150 and 275 kilograms, and possess the largest eyes in the animal kingdom, reaching up to 30 centimeters across, roughly the size of a large pizza.

Overall, the study identified 226 species spanning 11 major animal groups, including squid, marine mammals, cnidarians, echinoderms, and unusual deep-sea fish.

Scientists also detected dozens of species never previously recorded in Western Australian waters. These included the sleeper shark (Somniosus sp.), the faceless cusk eel (Typhlonus nasus), and the slender snaggletooth (Rhadinesthes decimus).

Lead author Dr. Georgia Nester conducted the research during her PhD studies at Curtin University and now works at the Minderoo OceanOmics Centre at The University of Western Australia. She said the findings demonstrate how little scientists still know about Australia's deep-sea environments.

"Finding evidence of a giant squid really captures people's imagination, but it's just one part of a much bigger picture," Dr. Nester said.

"We found a large number of species that don't neatly match anything currently recorded, which doesn't automatically mean they're new to science, but it strongly suggests there is a vast amount of deep-sea biodiversity we're only just beginning to uncover."

How eDNA Is Transforming Ocean Exploration

WA Museum Head of Aquatic Zoology and Curator of Molluscs Dr. Lisa Kirkendale said there have only been two previous records of giant squid in Western Australia, with no confirmed sightings or specimens collected for more than 25 years.

"This is the first record of a giant squid detected off Western Australia's coast using eDNA protocols and the northernmost record of A. dux in the eastern Indian Ocean," Dr. Kirkendale said.

To carry out the research, Dr. Nester gathered water samples from the ocean surface to depths greater than 4 kilometers. The eDNA analysis was paired with genetic reference material from physical specimens collected by the remotely operated vehicle SuBastian.

Taxonomists identified the collected specimens, which are now stored permanently in the WA Museum's Collection and Research Facility to support future research.

"The WA Museum contributed expert identification of specimens from the expedition, supporting the development of a local curated genetic reference that strengthened the eDNA analyses," Dr. Kirkendale said.

Dr. Nester explained that eDNA is especially valuable for detecting fragile, fast-moving, or elusive marine species that may escape traditional nets and underwater cameras.

"These canyons are incredibly rich ecosystems and, until now, they've been largely unexplored because of the difficulty of working at such extreme depths," Dr. Nester said.

"With eDNA, a single water sample can tell us about hundreds of species at once."

"That means we can dramatically expand our understanding of deep-water environments in a way that simply hasn't been possible before."

Hidden Ecosystems Beneath the Indian Ocean

The research also showed that marine life changes significantly with ocean depth. Even neighboring canyons supported different ecosystems and distinct biological communities.

Senior author Associate Professor Zoe Richards from Curtin's School of Molecular and Life Sciences said the technology could dramatically improve how scientists study and protect deep-sea ecosystems.

"Deep-sea ecosystems are vast, remote and expensive to study, yet they face growing pressure from climate change, fishing and resource extraction," Associate Professor Richards said.

"Environmental DNA gives us a scalable, non-invasive way to build baseline knowledge of what lives there, which is essential for informed management and conservation.

"You can't protect what you don't know exists. The sheer number of discoveries, including megafauna, makes it clear that we still have so much to learn about what marine life lives in the Indian Ocean."

Dr. Nester said gaining a better understanding of deep-sea biodiversity could help improve marine park planning, environmental monitoring, and conservation efforts over time.

"By combining eDNA with conventional deep-sea survey techniques, we can build a far more complete picture of biodiversity, revealing species, ecosystems and ecological patterns that would otherwise remain hidden," she said.

"This kind of information is critical for marine park planning and management, because it gives us a much clearer picture of what species are present and how communities are structured across depth."

The fieldwork was supported by the Schmidt Ocean Institute and the Western Australian Museum. The project involved researchers from Curtin University, UWA, The Western Australian Museum, the Minderoo OceanOmics Centre at UWA, the University of Tasmania, and Research Connect Blue.

The study, titled "Environmental DNA Reveals Diverse and Depth-Stratified Biodiversity in East Indian Ocean Submarine Canyons," was published in the journal Environmental DNA.