Ten Strange Medieval Animals You Might Not Have Heard Of

Bestiaries were created in the Middle Ages to catalogue the various creatures that lived around the world. They would include various animals like horses and lions, along with more fantastical creatures such as dragons and unicorns. Here are ten creatures that are less known but have unusual characteristics. Some were based on real animals, while the origins of others remain a mystery.

Barnacle Goose

British Library Harley MS 4751, Folio 36r
British Library Harley MS 4751, Folio 36r

Barnacle Geese were thought to be birds that grew from trees. Gerald of Wales gives this explanation:


They are produced from fir timber tossed along the sea, and are at first like gum. Afterwards they hang down by their beaks as if they were a seaweed attached to the timber, and are surrounded by shells in order to grow more freely. Having thus in process of time been clothed with a strong coat of feathers, they either fall into the water or fly freely away into the air. They derived their food and growth from the sap of the wood or from the sea, by a secret and most wonderful process of alimentation. I have frequently seen, with my own eyes, more than a thousand of these small bodies of birds, hanging down on the sea-shore from one piece of timber, enclosed in their shells, and already formed. They do not breed and lay eggs like other birds, nor do they ever hatch any eggs, nor do they seem to build nests in any corner of the earth.

They were considered to be so strange during the Middle Ages that Pope Innocent III banned Catholics from eating these geese during Lent.



ten strange medieval animals
A Bonnacon, from Kongelige Bibliotek, Gl. kgl. S. 1633 4º, Folio 10r

According to the Aberdeen Bestiary, “in Asia an animal is found which men call Bonnacon. It has the head of a bull, and thereafter its whole body is of the size of a bull’s with the maned neck of a horse. Its horns are convoluted, curling back on themselves in such a way that if anyone comes up against it, he is not harmed.

But the protection which its forehead denies this monster is furnished by its bowels. For when it turns to flee, it discharges fumes from the excrement of its belly over a distance of three acres, the heat of which sets fire to anything it touches. In this way, it drives off its pursuers with its harmful excrement.”


A Crocotta, as portrayed in the Aberdeen Bestiary
A Crocotta, as portrayed in the Aberdeen Bestiary

The ninth-century Byzantine scholar Photius wrote that “in Ethiopia there is an animal called crocottas, vulgarly kynolykos (dog-wolf), of amazing strength. It is said to imitate the human voice, to call men by name at night, and to devour those who approach it. It is as brave as a lion, as swift as a horse, and as strong as a bull. It cannot be overcome by any weapon of steel.”

Meanwhile, a 13th-century English bestiary states this animal comes from India and is “swifter than all other wild beasts. It is as big as an ass; it has the hindquarters of a stag, the chest and legs of a lion, the head of a horse and cloven hooves. Its mouth stretches from ear to ear. Instead of teeth it has a continuous bone. So much for its shape; with its voice it imitates the sound of speech.”




Isidore of Seville writes “The echinais has its name because it clings to a ship and holds it fast (echei-naus). It is a small fish, about six inches long, but when it attaches to a ship the ship cannot move, but seems rooted in the sea, despite raging storms and gales. This fish is also called “delay” (mora) because it causes ships to stand still.”


Hydrus in British Library MS Royal 12 C XIX f. 12v
Hydrus in British Library MS Royal 12 C XIX f. 12v

The hydrus lived in the Nile River and was the enemy of the crocodile. When it sees a crocodile sleeping with its mouth open, the hydrus first rolls in mud to make itself slippery, then enters the crocodile’s mouth and is swallowed. It then eats its way out of the crocodile’s belly, killing it.

St Antony of Padua explains how the Apostles of Jesus Christ were similar to these creatures:


There is a certain little serpent which rolls itself in the mud, and thus enters the mouth of the sleeping crocodile, who wakes up and swallows it down; on which it eats through his entrails, and comes out through his side. Thus the Apostles, rolled as it were in the mud of poverty and humility, leapt boldly into the mouths of tyrants, and openly contradicted their words of unbelief, and were thus devoured by death. Nevertheless, these tyrants themselves were slain by their means, and the Apostles came forth alive from them, when their death redounded to the augmentation of the faith and to the honour of Christ.


Monoceros - from British Library MS Sloane 3544 f. 9v
Monoceros – from British Library MS Sloane 3544 f. 9v

Here is a creature that seems quite similar to unicorns. According to a 13th-century Bestiary from England (MS Bodley 764), “the monoceros is a monster with a horrible bray; it has the body of a horse, the feet of an elephant and a tail like that of a stag. A horn of extraordinary splendour projects from the middle of its forehead, for feet in length, and so sharp that anything it strikes is easily pierced by the blow. It is never taken into the power of human beings while it lives; it can be killed but never captured alive.”


Parandrus - from British Library MS Royal MS 12 C XIX;
Parandrus – from British Library MS Royal MS 12 C XIX;

According to Brunetto Latini the Parandrus lives in Ethiopia and had the tracks of an Ibex, the branching horns of a Stag, the colour of a Bear, and, like a bear, it has a shaggy coat. It is believed to change colour into a likeness of whatever it is close to.


Sawfish - British Library MS Sloane 278 f.51
Sawfish – British Library MS Sloane 278 f.51

From a 13th-century Bestiary by Hugh of Fouilloy:

There is a beast in the sea which is called a sawfish, and has immense wings. When this beast has seen a ship making sail on the ocean, it raises its wings above the water and competes with the ship in sailing. (But when it has competed in sailing or racing against the ship) for 30 or 40 furlongs, being unable to sustain the exertion, it gives up, and lowering its wings draws them in. And the waves of the sea carry it back again, tired out, to its own place in the deep.




Isidore of Seville explains “the wether is named either from its strength because it stronger than other sheep; or because it is male or because it has worms in its head. When excited by an itch they strike one another with great force.”


Yale - British Library MS Royal 12 F XIII f. 27
Yale – British Library MS Royal 12 F XIII f. 27

According to the Aberdeen Bestiary: “There is an animal called the yale. It is black, as big as a horse, with the tail of an elephant, the jaws of a boar and unusually long horns, adjustable to any movement the animal might make. For they are not fixed but move as the needs of fighting require; the yale advances one of them as it fights, folding the other back, so that if the tip of the first is damaged by a blow, it is replaced by the point of the second.”

You can learn more about medieval bestiaries at and read the Aberdeen Bestiary at You can also read these articles:

Ten Strange Medieval Ideas about Animals

The Beauty of the Bestiary

The Bestiary of Anne Walshe

Northumberland Bestiary now online

De Herinacio. On the Hedgehog