Environmental DNA reveals evidence of giant squid (and other never-before-seen species) in underwater canyons off the coast of Ningaloo

In the heart of the Indian Ocean, at depths where eternal darkness reigns, they hide abysmal creatures So elusive that they have fueled centuries of legends and tales. A recent expedition off Western Australia, however, has demonstrated that to discover where these mythological "sea monsters" live, you don't necessarily need to meet them: you just need to know how to read the invisible traces they leave in the water. Through the analysis of the Environmental DNA, a team of scientists has opened a new window into marine ecosystems that we are just beginning to discover.

Australia: eDNA reveals the most elusive inhabitants of underwater canyons.

Species never before identified in that area and others that are believed to be even new to science: this is what researchers from Curtin University and the Western Australian Museum discovered when, aboard the research vessel Falkor of the Schmidt Ocean Institute, they explored the deep submarine canyons of Cape Range and Cloates, about 1200 km north of Perth. By collecting over a thousand samples from depths of up to 4510 meters and using environmental DNA, scientists were able to document the species that live in these deep-sea habitats without needing to see or capture them.

Among the most striking findings are certainly the traces of the Giant Squid (Doge Architeuthis), detected in both the Cape Range and Cloates Canyon in six separate samples, but also those of deep-sea cetaceans such as the Blainville's cogia (kogia breviceps) and the Cuvier's beaked whale (Ziphius cavirostris). The study describing these findings, just published in Environmental DNA, he identified 226 species belonging to 11 animal groups, including rare deep-sea fish, cnidarians, echinoderms, squid, and marine mammals.

Among the dozens of species never before documented in Western Australian waters, sharks of the genus Somniosus (Somniosus sp.), the Typhlonus nasus and Rhadinesthes decimus.

The giant squid, the mysterious "monster" that populates the deep

In the novel “The Tale of the Troika”, by the brothers Arkadij and Boris Strugatsky, the Spiridon giant squid he speaks of the sperm whale as his “only old personal enemy”. And in fact, if the sperm whales were not voracious predators of the squid species Doge Architeuthis, we would know practically nothing about them.

Le first images of a live giant squid in its natural environment date back to 2004: researchers from the National Museum of Science of Japan and the Ogasawara Whale Watching Association published some of those photos the following year. And in 2006, on December 4, the same team managed to filming for the first time An adult giant squid near the Ogasawara Islands, a thousand kilometers south of Tokyo. It was a small specimen, a female that was killed during collection operations.

Even today, almost exclusively the remains found inside sperm whales allow us to estimate the true size of these animals. They are thought to reach 18 meters in length, with a maximum estimated weight of 150 kilograms for females and 275 kilograms for males. They are believed to live between 200 and 1000 meters deep, and that they reach their considerable size very quickly, probably by the age of 3 years. We do know, however, that their eyes—which have a diameter of up to 30 centimeters—are the largest in the entire animal kingdom.

The discovery of the giant squid off the coast of Ningaloo once again brings us face to face with a disarming realization: deep-sea ecosystems are still largely unknown.

“Finding evidence of a giant squid really captures the imagination, but it's only part of a much bigger picture,”

explains Georgia Nester, lead author of the study.

eDNA to Unravel Mysteries Hidden at the Ocean's Bottom

The doctor Lisa Kirkendale, head of aquatic zoology and curator of molluscs at the WA Museum, said there were only two other reports of giant squid in Western Australia, but also stressed that there were no sightings or specimens recorded since over 25 yearsThis, however, is the first report obtained through eDNA analysis:

“This is the first report of a giant squid off the coast of Western Australia using eDNA protocols and the northernmost report of A. dux in the eastern Indian Ocean,”

he has declared.

During the operations, Dr. Nester collected water samples at various depths, from the surface to over 4.000 meters, and combined the eDNA analysis with reference genetic sequences from physical specimens collected by the renowned remotely operated underwater vehicle SuBastian. Then, as Kirkendale explained,

“The WA Museum contributed expert identification of the expedition specimens, supporting the development of a curated local genetic reference that strengthened the eDNA analyses.”

Environmental DNA has allowed scientists to identify fragile, rare and very fast species – which would perhaps be impossible to detect with traditional means, such as cameras and networks:

“These canyons are incredibly rich ecosystems and, until now, have remained largely unexplored due to the difficulty of operating at such extreme depths,”

Dr. Nester said. Her words are echoed by Kirkendale's:

“We found a large number of species that don’t perfectly match any currently recorded species, which doesn’t automatically mean they’re new to science, but it strongly suggests that there’s a vast, deep-sea biodiversity that we’re only now beginning to discover.”

Environmental DNA: Understanding Life to Protect It

Thanks to eDNA, the researchers explain, a single water sample can provide valuable information on hundreds of species at the same time, and this allows us to significantly expand our understanding of deep-sea ecosystems. For example, it has been discovered that adjacent canyons can support very different ecosystems.

According to the teacher Zoe Richards, from Curtin University's School of Molecular and Life Sciences, eDNA has the potential to transform the way scientists explore and protect the ocean depths:

Deep-sea ecosystems are vast, remote, and expensive to study, yet they are under increasing pressure from climate change, fishing, and resource exploitation. Environmental DNA offers us a scalable and non-invasive method to gain basic knowledge about what lives in these environments, essential for informed management and conservation.

Continue to investigate the depths to get a more precise picture of theecology of deep-sea ecosystems Above all, it serves to give us the concrete possibility of protecting marine species that still elude our understanding:

"You can't protect what you don't know exists. The sheer number of discoveries, including megafauna, clearly demonstrates that we still have a great deal to learn about the marine life that populates the Indian Ocean."

concludes Richards.

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