Aspidochelone

Also Known As: Greek ἀσπιδοχελώνη, “asp-turtle” or “shield-turtle”; called Fastitocalon in Old English, Jasconius in the Irish voyage of Saint Brendan
Region/Culture: Western Europe
Mythos: Christian Mythology, Medieval Mythology
Primary Type/Nature: Monsters and Beasts
Mythical Attributes: It counterfeits an island well enough to hold a moored ship, and it breathes a sweet smell that walks fish into its mouth.
Role in Mythos: In the Physiologus and the bestiaries that copied it, the beast is the working model of the Devil, and every detail of its behaviour is read as a detail of his.
Relation to Humans: It does not hunt sailors so much as wait for them to make themselves comfortable. The men who die on its back are killed by their own relief, and by the fire they lit to celebrate having found solid ground.

The fire was the mistake. Brendan’s monks had put in at a low shelf of rock with no grass on it, no sand along the water, barely enough wood to be worth gathering, and after a night of prayer outside the boat and a morning of Mass they carried out the raw meat they had salted and set a cauldron over a flame. They fed the fire. The pot came to the boil. Then the island began to move under them like a swell, and the brothers ran for the hull leaving supper, kettle and provisions where they lay. From more than two miles off they could still see their own fire burning, riding away across the ocean on something that was not land. Brendan, who had known all along and had said nothing rather than frighten them, explained it afterwards: not an island, a fish, the greatest of all that swim, forever trying to bring its tail round to meet its head and never managing it because of the length of its body. Its name was Jasconius, which is only the Irish word for fish with a Latin coat on.

That is the friendliest version of the story. The Greek one, older and colder, gives the creature a name that has puzzled everyone who has looked at it: aspidochelone, an asp welded to a turtle, or possibly a shield welded to a turtle, which is a strange thing to say about an animal that already comes with a shield. It surfaces in the Physiologus, the Alexandrian book that took forty-nine chapters of animals and natural things and read each one as a sermon. Nobody agrees on when that book was assembled. The estimates swing across several centuries either side of the turn of the era, and the compiler left no name. What is certain is that it travelled. It was in Latin before the fifth century was out, and from there it went into every bestiary the Latin west produced, carrying the asp-turtle with it the whole way.

The Old English poet who took it up for the Exeter Book gave it the best physical account it ever received. His whale is dun, the colour of weathered stone, and it lies on the water looking exactly like a tidal reed-bed with dunes behind it, the sort of low unremarkable coast a tired crew stops looking at closely. He calls it the swimmer of the ocean-streams and, in a line that has kept its shock for a thousand years, describes the crews mooring their high-prowed ships with cables to that unlond, that not-land. They tie up. They climb ashore. They build a fire because they are cold and pleased with themselves, and they settle down to enjoy the weather. The poem is very precise about the trigger: the beast waits until it feels the men are firmly established on it, until they have stopped being wary. Then it goes down, straight down, with the ships still tethered, and takes them to the bottom.

There is a second trick, and the bestiaries liked it even better than the first. When the creature is hungry it simply opens its mouth. Out of it comes a smell so sweet that the smaller fish turn and swim towards it, gathering in the dark of that gullet in numbers, unhurried, delighted. The Aberdeen Bestiary describes them arriving in a crowd. When the mouth is full, it shuts. The manuscripts put the two habits side by side because they are the same habit twice: something enormous that does not chase anything, and never needs to.

The moral was never subtle and was never meant to be. The false island is the Devil offering solid ground to men of no faith, and the sweet breath is the Devil offering pleasure to men of small faith, and the jaws closing are the gates of hell, which the Old English poem says shut on the damned exactly as they shut on the fish, with the same finality and the same lack of exits. The poet even gives the Devil a helmet of darkness to wear on the way down. It is the kind of allegory that works because the picture underneath it is genuinely frightening and would be frightening with the theology stripped out.

Its powers all descend from a single fact, which is that it is too big to be recognised as an animal. Scale is the whole of the trick. A creature that can be walked on does not need speed, venom, teeth or malice; it needs only patience and the human habit of trusting anything that holds still. The sweet breath works the same way on fish, substituting appetite for the sense of danger. Against that, the weaknesses are almost comic. It can be beaten by anyone who simply knows what it is, which is why Brendan slept in the boat and walked away with every man he had brought. It is betrayed by heat, since it is the cooking fire, not the weight of men, that makes it dive and gives the game away. And by the Navigatio’s own account it cannot even fold itself comfortably, straining year after year to touch its tail to its head and failing every time, an immensity that is also a nuisance to its owner.

There is a last small irony in the archive. The Aberdeen Bestiary’s whale chapter now begins in the middle of a sentence about unbelievers being dragged down into fire, because the leaf that carried the island episode has gone missing from the quire. The one page that told you how the beast swallows people is the page the book lost.

Frequently Asked Questions

What is the Aspidochelone?

The Aspidochelone is a gigantic sea creature from the Physiologus and the medieval bestiaries that descended from it, so large that sailors mistake its back for an island. It is described as part turtle and part whale, with a hide the colour of rough stone. When crews moor to it and light a fire, it dives and drowns them.

Why does the Aspidochelone sink ships?

The Aspidochelone waits until the sailors on its back have relaxed and settled in, then plunges to the sea floor with their ships still tied to it. In the Old English poem about the beast the men are killed by their own sense of safety, having moored to what the poet calls a land that is no land.

What does the Aspidochelone symbolise?

In Christian bestiary tradition the Aspidochelone stands for the Devil. The false island represents Satan offering solid footing to those with no faith, its sweetly scented breath represents temptation catching those of weak faith, and its closing jaws represent the gates of hell shutting on the damned.

What is the connection between the Aspidochelone and Saint Brendan?

The Irish Navigatio Sancti Brendani tells the same story with a named beast called Jasconius, from the Irish word for fish. Brendan’s monks celebrate Mass on its back and set a cauldron over a fire, and when the pot boils the island moves off beneath them. Brendan had recognised it in advance and had kept quiet to spare his monks the fear.

Where does the name Aspidochelone come from?

The name is Greek, combining aspis, meaning asp or shield, with chelone, meaning turtle, giving either asp-turtle or shield-turtle. Old English speakers reshaped it into Fastitocalon for the poem in the Exeter Book, where the added initial F lets the name carry the alliteration that Old English verse required.