In 2011, scientists recorded a previously unknown feeding strategy in whales. Now researchers in Australia think they’ve found evidence of the same behavior being recorded more than 2,000 years ago. Specifically, in texts that describe ancient accounts of sea creatures. Meaning this recently rediscovered behavior may be the key to understanding the legends behind these mythical monsters.

The rediscovered behavior is whales staying near the surface of the water with their jaws open at right angles. This strategy makes shoals of fish think they have found a place to take shelter from predators. When in reality they are literally swimming into the jaws of danger. This is a serious deviation from their normal behavior of lunging at their prey. A clip of this unusual feeding style was posted to Instagram in 2021 where it went viral.
After seeing the clip Dr. John McCarthy, a maritime archaeologist at the College of Humanities, Arts and Social Sciences at Flinders University, started to connect the dots. While McCarthy was reading about Norse sea monsters he started to notice parallels between this feeding behavior and the myths.
“It struck me that the Norse description of the hafgufa was very similar to the behaviour shown in videos of trap feeding whales, but I thought it was just an interesting coincidence at first,” explains McCarthy. “Once I started looking into it in detail and discussing it with colleagues who specialise in medieval literature, we realised that the oldest versions of these myths do not describe sea monsters at all, but are explicit in describing a type of whale.”
“That’s when we started to get really interested. The more we investigated it, the more interesting the connections became and the marine biologists we spoke to found the idea fascinating.” As you can see from the clip, those massive jaws hanging out above and below the water are intimidating even with context. Now imagine it being someone seeing that 2,000 years ago with little to no context for what a whale is. It’s no wonder they thought they were monsters.

The connections mostly come from 13th-century Norse manuscripts describing a creature called the hafgufa. The hafgufa held a place in Icelandic mythology until around the 18th century. It’s also possible that these myths drew inspiration from medieval bestiaries. Which popular texts at the time that describe large numbers of real and fantastical animals. A creature called the aspidochelone often appears in these bestiaries and their description is very similar to the hafgufa.
Both creatures are said to emit a special scent that helps to draw the fish toward their stationary mouths. Researchers theorize this may be based off the ejection of filtered prey by whales. Which dose to help attract more prey into a whale’s open mouth.

“It’s exciting because the question of how long whales have used this technique is key to understanding a range of behavioural and even evolutionary questions. Marine biologists had assumed there was no way of recovering this data but, using medieval manuscripts, we’ve been able to answer some of their questions,” said research co-author Dr Erin Sebo, an Associate Professor in Medieval Literature and Language in the College of Humanities, Arts and Social Sciences at Flinders University.
It is still not known why this strategy has only recently been recorded again. It’s speculated whales may have started doing this again due to changing environmental conditions. Or it could be we are just observing more of their behavior with more modern technology like drones.
You can check out the full paper here.