Meet the 19-metre octopus that prowled the ancient seas

Researchers have uncovered evidence suggesting that massive octopuses might have dominated the prehistoric oceans alongside dinosaurs, challenging long-held beliefs about marine predators. Fossilized jaws, recently examined, hint at the possibility of these creatures reaching lengths up to 19 meters, potentially surpassing all known invertebrates in size. This discovery shifts the narrative about ancient ocean ecosystems, where vertebrates like fish and reptiles were once considered the primary hunters.

Ancient Predators Reimagined

Until now, scientists assumed that the largest ocean predators were vertebrates, while invertebrates like octopuses and squid occupied secondary roles. However, a new study by Japanese researchers at Hokkaido University proposes that giant octopuses could have been formidable top predators. Their analysis indicates these creatures possessed jaws capable of crushing shells and bones, allowing them to tackle prey such as large marine reptiles and fish.

The research estimates that these ancient octopuses had body lengths between 1.5 and 4.5 metres. When accounting for their lengthy arms, the total length might have spanned 7 to 19 metres. Even at the smaller end of this range, they would have been significantly larger than today’s species. For example, the Giant Pacific Octopus, the biggest living octopus, typically has an arm span exceeding 5.5 metres.

Feeding Habits and Intelligence

One intriguing detail from the fossilized remains is the asymmetrical wear on the jaws, implying a preference for one side during feeding. This trait, observed in modern octopuses, is associated with advanced cognitive abilities. Contemporary octopuses are renowned for their problem-solving skills and complex hunting techniques, suggesting their ancient relatives may have shared these traits.

“With their tentacles and suckers, they could perfectly hold on to such an animal and there is no escape,” remarked Christian Klug, a palaeontologist at the University of Zurich, who assessed the findings.

Despite these insights, many questions linger. Scientists cannot definitively determine the exact form of these creatures, the size of their fins, or their swimming speed. Additionally, no fossils have been found containing stomach contents, leaving uncertainty about their diet. Dr. Nick Longrich of the University of Bath speculates that ammonites may have been a primary food source, though these octopuses likely adapted to hunt any available prey.

For now, the fossils provide a fascinating window into a once-mighty sea creature. Equipped with a crushing jaw, robust arms, and a brain that might have enabled competition with other apex predators, this ancient giant remains a subject of intrigue. The study, published in the journal Science, highlights the need for further exploration to unravel the full story of these enigmatic marine beings.