This time I will with poetic art rehearse, by means of words and wit, a poem about a kind of fish, the great sea-monster which is often unwillingly met, terrible and cruel-hearted to seafarers, yea, to every man; this swimmer of the ocean-streams is known as the asp-turtle.
His appearance is like that of a rough boulder, as if there were tossing by the shore a great ocean-reedbank begirt with sand-dunes, so that seamen imagine they are gazing upon an island, and moor their high-prowed ships with cables to that false land, make fast the ocean-coursers at the sea's end, and, bold of heart, climb up on that island; the vessels stand by the beach, enringed by the flood.
The weary-hearted sailors then encamp, dreaming not of peril.
On the island they start a fire, kindle a mounting flame. The dispirited
heroes, eager for repose, are flushed with joy. Now when the cunning
plotter feels that the seamen are firmly established upon him, and have
settled down to enjoy the weather, the guest of ocean sinks without
warning into the salt wave with his prey (?), and makes for the bottom,
thus whelming ships and men in that abode of death.
Such is the way of demons, the wont of devils:
The poem continues, explaining another trait of the monster: when it is hungry, it opens its enormous maw, from which a "perfume" emanates that draws a host of fish inside, when it then snaps its jaws shut. This suggests that sailors may have actually seen a whale opening its mouth to feed.
Fastitocalon is the name given to the creature, but that is the Old English version of the original. The poem (and two others) is found in a Bestiary called the Old English Physiologus, part of the Exeter Book. In the Latin version, the creature is called aspidochelone, combining Greek aspis (shield) and chelone (turtle). The Old English version has become more popular (and familiar) thanks to Tolkien writing a poem of that name in The Adventures of Tom Bombadil.
Where did the story of this giant sea-creature-as-island originate? There is a Greek Alexander Romance written in the first few centuries CE that contains a whale-island anecdote in a letter from Alexander to Aristotle. The first voyage of Sinbad (composed c.8th-9th centuries CE) tells a similar tale. Pliny the Elder talks about enormous fish as well. The Babylonian Talmud and Inuit of Greenland folklore both contains legends of a fish so large that it resembled an island and inspired sailors to land on its back. There are many more examples from different parts of the world.
Even St. Brendan encountered it, and gave it a name that has since been used by the Magic: The Gathering card game. I'll share more tomorrow.