The whale stopped vertically in the sea, motionless, raised its head and opened its mouth, and its mouth and nose protruded from the water, like a cave at a ninety degree angle erected at sea level. Small fish jumped up. Not long after, the big whale closed its mouth, and the small fish were "swallowed".
It was only in the 2010s that scientists observed this peculiar way of predation by cetaceans. In 2011, Bryde's whale in the Gulf of Thailand opened its jaws at right angles to the water, a behavior scientists call "tread-water feeding." Around the same time, humpback whales near Vancouver Island, Canada, exhibited similar behavior and were dubbed "trap-feeding."
Recently, however, it has been discovered that this unusual predation technique was documented two thousand years ago.
Dr. John McCarthy, a marine archaeologist at Flinders University in Adelaide, Australia, read Norse mythology when he discovered a sea creature called hafgufa, which seemed to be described exactly as described above. Hafgulfa, literally meaning "sea steam", is believed to be a sea monster that haunts waters near Greenland. "What a coincidence." McCarthy said he read the ancient text a year after seeing videos of cetaceans treading water to eat. His study with his companions was published in the February 2023 issue of Marine Mammal Science.
John McCarthy's diagram of humpback whale trap predation
There is more than one description of this behavior in ancient texts. The earliest description appears in the Physiologus, a Greek manuscript written in Alexandria before the middle of the second century AD, second only to the Bible in popularity in the early Middle Ages. The book preserves zoological information brought to Egypt from India and the Middle East, derived from natural historians (including Herodotus, Kertesias, Aristotle, and Plutarch), merchants, and travelers. The compilers considered the descriptions of the flora, fauna and terroir to be "true" by the natural sciences, so they called themselves "naturalists", although they also recorded sirens, sirens, unicorns and other creatures of human fantasy.
In the Naturalist, the ancient Greeks called the creature aspidochelone, which means shield turtle. An extant version describes it as follows: "When it is hungry, it opens its mouth and exhales from it a pleasant smell that once detected by small fish, they gather in its mouth." But when its mouth is filled with all sorts of small fish, it suddenly closes its mouth and swallows them. ”
The most detailed description appears in the mid-13th century Old Norse Konungs skuggsjá (The Mirror of the King): "We call it the Hafgufa... When foraging... This big fish opened its mouth for a while, its mouth opened like a large fjord, and before it knew it, schools of fish poured in. After filling his belly and big mouth, [Hafgula] closed his mouth, so that all the prey that came to hunt for food was swept up and hid inside. ”
The Mirror of the King, a book for the education of monarchs, preserves records of real and false marine life in North Atlantic waters. For a long time, the Hafgufa was considered "to be classified as a fantasy world". But McCarthy says that while the narrator exaggerates the size... But not a completely supernatural fantasy description.
Codex of the Mirror of the King, circa 1250
McCarthy added: "The Hafgu method frustrates these scholars because they don't understand what kind of animal it corresponds to. "After all, scholars at the time couldn't tell the difference between fish and marine mammals." Now, we think we have an explanation. ”
They believe that the key to the success of this predation technique is that the whale's wide open mouth seems to provide an obvious shelter, and small fish will instinctively rush towards it. In fact, not only small fish will be misidentified, but also humans. People think it's an island. In the story of Sinbad the navigator in "One Thousand and One Nights", the passengers on board land on the island to rest halfway. While they were lighting a fire to cook, the captain noticed that the island was shaking - "This is not an island, but a huge fish floating on the water!" He shouted for everyone to hurry up and get on board, because if the big fish shaken by the heat sinks to the surface, the people on the "island" will die. Melville's Moby Dick also depicts a large whale as an island: "The big whale is rolling its island-like body in the desolate vast sea. In the librarian's selection at the beginning of the novel, there are also several poets who see the same thing, such as Milton's "Paradise Lost":
"That Leviathan
The biggest animal, like a headland
Sleep in the sea, swim,
Like a flowing piece of land, its gills suck in
A sea that spews out the sea again. ”
Montgomery, The World Before the Flood:
"From the dreaded leviathan to the insect,
Countless biological cluster waves,
Whales, sharks, behemoths,
They are guided by mysterious instincts,
Crowds, like floating islands"
The image of a person cooking on the island being overturned by a large fish was made around 1270
The researchers find it interesting that cetaceans' "feeding pattern has been documented thousands of years ago, but in recent years has been described as a new technique" and reasoned that "trap predation is likely to only be used in the presence of other predators," as this is observed in individual whales and is not a social predation activity. "It has low physical requirements for whales, so it only makes the most sense when there are only smaller schools of fish left after the predatory binge." Some researchers believe that when the density of fish stocks is very low, whales will also use this way of saving physical energy, because too much effort is obviously not rewarded.
Editor: Chunyi Li