The Great White Shark: The Largest Invertebrate Predator in History

The Cretaceous seas were once dominated by a formidable giant octopus species, potentially reaching lengths of up to 19 meters, rivaling the era’s most intimidating predators, including sharks and marine reptiles such as plesiosaurs and mosasaurs.

According to Yasuhiro Iba from Hokkaido University, these octopuses acted as apex predators in their ecosystem. “They can be likened to the killer whales or great whites of the invertebrate realm—large, intelligent, and proficient hunters,” states Iba. These colossal beings boasted over 10 meters in length with robust arms and powerful jaws designed to crush hard prey, likely displaying complex behaviors.

Researchers, including Iba and his colleagues, analyzed 27 large octopus jaw fossils dating from 100 million to 72 million years ago, discovered in Japan and Vancouver Island, Canada. Remarkably, over a dozen of these jaw fossils, previously unseen by science, were unearthed through “digital fossil mining,” leveraging advanced scanning technology and AI to reveal the octopus remains embedded within stone.

The jaw, or beak, is often the only surviving fossil component of an octopus, made primarily of durable chitin, while the softer parts decay.

Initially thought to comprise five Cretaceous octopus species, recent research indicates that only two have been identified to date: Nanaimoteutis zeretskyi and N. hagarti.

Iba notes, “We quickly observed the jaw’s unusual size, especially that of N. hagarti. It stood out even among modern large cephalopods.” The true scale emerged from correlating the jaw’s size to the length of the mantle in contemporary long-bodied octopuses, estimating that N. hagarti may have reached overall lengths between 6.6 and 18.6 meters, marking it as one of Earth’s largest invertebrates.

John Long, a professor at Flinders University in Australia, expressed that he was unsurprised by this finding. “Many creatures during the Cretaceous period exhibited gigantism, including sharks, marine reptiles, and ammonites, filling the ocean with ample prey for large predators,” he said, while acknowledging the surprising nature of finding giant killer octopuses as apex predators of the Cretaceous seas.

Notably, ancient octopuses bore a resemblance to modern giant squids (Architeuthis dux), which can grow beyond 12 meters. However, as Iba points out, they possessed distinct traits. Squids feature eight arms and two long tentacles for captures, while octopuses utilize all eight arms effectively to ensnare prey.

Nanaimoteutis likely did not pursue prey like squids but rather employed their lengthy, flexible arms for capture, complemented by their formidable jaws for processing.” The researchers also scrutinized wear patterns on ancient jaws, indicating substantial “hard material processing,” implying they preyed on robust organisms like large bivalves, ammonites, crustaceans, fish, or other cephalopods.

While the intuition might suggest they hunted massive creatures, careful consideration is warranted. “No direct evidence,” says Iba, “indicates predation on marine reptiles or sharks, such as stomach contents or bite marks on vertebrate bones.”

Another noteworthy observation was the uneven wear on the jaws, suggesting a phenomenon known as “lateralization.” This behavioral preference for one side of the body may indicate a level of intelligence, echoing characteristics seen in modern octopuses.

Overall, lateralization is linked to sophisticated brain function and efficient information processing. “The asymmetrical wear on our fossil jaws implies these octopuses had individual feeding preferences,” asserts Iba, highlighting their physical strength, behavioral complexity, and possible unique tendencies.