Kraken? Mermaid? Mythical Sea Monsters May Have Been Whales Acting Weirdly

A mysterious whale behavior that was only recently observed by scientists may explain seemingly fantastical historical accounts of sea monsters, according to a study.

Researchers found evidence that humans may have been documenting the strange behavior for centuries, from around 2,000 years ago.

The study, published in the journal Marine Mammal Science, details how ancient and medieval peoples may have witnessed this behavior. Earlier accounts show that the creature was understood to be a type of whale. However, these descriptions are often exaggerated or embellished with surrealistic details.

But, in more recent centuries, these older accounts may have been misinterpreted as depicting fantastical sea creatures like the kraken and even mermaids.

The translation “Icelandic Physiologus” (circa 1200 A.D.) depicts a whale-like sea creature feeding. A study has uncovered parallels between animals described in historical records and a mysterious whale behavior that was identified only recently.
Reykjavík AM 673 a II 4to fol. 3v Public Domain, color and contrast corrected

The whale behavior refers to a feeding strategy first documented by modern scientists in the 2000s. It was seen in two whale species on opposite sides of the globe.

This strategy involves whales lurking motionless at the surface of the water with their mouths wide open. They then wait patiently for shoals of fish to swim into the water between their jaws before slamming them shut. The fish enter the jaws in the mistaken belief that they have found a safe place to shelter from predators.

This behavior was observed in humpback whales in the Northeast Pacific and dubbed “trap feeding.” Scientists also documented a very similar, but possibly distinct, behavior among Bryde’s whales in the Gulf of Thailand. They named it “tread-water feeding.”

John McCarthy, a maritime archaeologist at Flinders University, in Adelaide, Australia, and author of the study, told Newsweek: “The first observations of this whale feeding strategy were made in 2011 by marine biologists working off Vancouver Island in Canada, but this was only reported in 2018, as a novel behavior named as trap-feeding.”

A digital reconstruction of a humpback whale trap-feeding. This strategy involves whales lurking motionless at the surface with their mouths wide open and waiting patiently for shoals of fish to swim into the water between their jaws.
J. McCarthy

“In 2017, another team in Thailand had reported a near-identical behavior in another species of whale, naming it as tread-water feeding,” McCarthy said. “It is not known if these are identical or just very similar behaviors. However, given that they are on opposite sides of the globe and in two different species, it does suggest the behavior may be relatively widespread among whales and used in different environments.”

It is still somewhat of a mystery why this behavior was documented by scientists only in the past few years. But researchers have speculated that increased monitoring of whales or shifting environmental conditions could be possible explanations.

The inspiration for the latest study came when McCarthy was reading about Icelandic mythology. He noticed curious similarities between historical writings and the recently observed feeding phenomenon.

Diagram of a humpback whale engaged in trap-feeding with the jaw in two different positions. The first observations of this whale feeding strategy were made in 2011 by marine biologists working off Vancouver Island in Canada.
J. McCarthy

“I have worked on shipwreck sites in Iceland and the North Atlantic, and have always been interested in the maritime history of the region,” McCarthy said. “I was casually reading about Icelandic mythology and came across a reference to a sea monster that trapped fish in its mouth by staying still at the surface of the water and enticing them to enter, before snapping its mouth shut to trap them.”

“This reminded me of a video I had seen online of a whale feeding in the same way,” McCarthy added. “After discussing the idea with experts in medieval literature, they turned up more and more data that seemed to support the theory that the two concepts were linked.”

McCarthy and his colleagues found previously unidentified but “striking” parallels between the characteristics of the recently observed feeding strategies and a marine creature described in ancient and medieval sources.

Known or suspected “aspidochelones” (fabled sea creatures, variously described as large whales or vast sea turtles) in several 13th-century medieval manuscripts. The aspidochelone first appeared in the “Physiologus”—an ancient manuscript written in Greek that originated in Alexandria, Egypt.
a) British Library MS. Harley 3244, fol. 65r, 1236, ca. 1250, Public Domain; b) Icelandic Physiologus, Reykjavík AM 673 a II 4to fol. 3v, ca. 1200, Public Domain; c) British Library Sloane MS 3544, ca. 1225–1275, Public Domain; d) Philippe de Thaon’s Bestiary, Oxford Merton College MS. 249 fol. 8r, ca. 1200, CC BY-NC; e Bodleian Library MS. Laud Misc. 247 fol. 157r, ca. 1240, CC-BY-NC; (f MS. Ludwig XV 3 (83.MR.173, fol. 89v, ca. 1270, Public Domain; (g Le Bestiaire Divin De Guillaume Clerc De Normandie, Bibliothèque nationale de France Français 14969, fol. 42v, Public Domain, 13th century (all color and contrast corrected

“This creature was known in ancient and medieval times as the ‘aspidochelone,’ and in Norse and later times as the ‘hafgufa,’,” McCarthy said. “It has generally been considered mythical or fantastical, but was listed alongside mostly real creatures now described by science. It may in fact be a fairly accurate description of a rarely observed whale feeding strategy.”

The hafgufa tradition can be traced back to the aspidochelone creature, which first appeared in the Physiologus—an ancient manuscript originally written in Greek. The manuscript was compiled by an unknown author in Alexandria, Egypt, and is thought to date from around the second century.

The Physiologus compiled information about creatures—real and fantastical—by early natural historians. It was later translated into several languages, including Icelandic around the year 1200.

An illustration from the Bern “Physiologus” labelled De Ceto Magno Aspidohelunes (meaning “On this great Aspidochelone”). Historical traditions of the aspidochelone seem to have understood the creature to be a type of whale.
Bern, Burgerbibliothek, Cod. 318fol. 15v: CC BY 4.0, color and contrast corrected

Historical accounts of the hafgufa/aspidochelone creature dating from ancient times all the way up to the 17th century seem to treat the animal as a type of whale. But, from that century onwards, misunderstandings of earlier descriptions of the creature begin to appear. These later scholars seem to confuse the hafgufa with fantastical creatures such as the kraken and even mermaids.

“After [the 17th century], writers became more confused about the creature for some reason, and it was said by some writers to be another name for the mythical kraken and therefore some kind of giant squid,” McCarthy said. “In fact, the kraken is a relatively modern invention, much more recent in time than the hafgufa/aspidochelone.

“The hafgufa has also been depicted in recent art as a giant turtle or a generic Godzilla-like creature, and there has been a lot of confusion because of these 18th-century writers,” McCarthy added.

“A recent video game called God of War even depicted the hafgufa as a gigantic jellyfish. However, we found that the earliest sources were clear and consistent over a remarkably long period in describing the creature as a type of large whale.”

Top, Ortelius’s 1658 map of Iceland showing various mythological sea creatures. Below, a detail of a sea creature labelled H. This was “the greatest of whales,” which could not chase fish but caught them through cunning.
Public Domain, color and contrast corrected

Where new descriptive details do appear in Norse accounts of the medieval period, McCarthy said they resemble the appearance of trap-feeding whales. They describe the creature’s mouth as appearing like two rocks jutting from the water.

The findings of the latest study raise the possibility that this feeding strategy may have existed in the distant past and is not a new phenomenon.

“If there is a real link between these phenomena, this suggests that the historical descriptions may be more reliable and contain more information about the ancient seas that we previously gave them credit for,” McCarthy said. “It may also inspire some new research directions for marine biologists who can further investigate how old these ‘novel’ behaviors really are.”

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“There is a lot left to learn about whale behavior. It is an exciting time in marine biology, with new technologies such as drones being used to sample whale breath as they surface,” McCarthy said.

The researchers even think, based on the ancient descriptions, that the trap-feeding whales may “bait” the water to draw in more prey by regurgitating small amounts of previous meals.

“It would be fantastic if this idea could be tested, although it might be difficult to get close enough to the whales at the right moment,” McCarthy said. ‘There is also the question of cultural transmission of whale behavior. Are these behaviors taught and potentially lost and reinvented over time, or are they simply instinctive?”