Everyone knows of mermaids, and some are even aware of their Greek origins: as a seafaring culture, the ancient Greeks had several sea creatures that fit the bill, from sirens to nereids and naiads. Not many are familiar with the wide range of sea monsters that threatened an honest sailor’s life according to ancient Greeks, many of which have found their way into modern tales. Here’s a look at some of them, courtesy of the Greek Reporter and Wikipedia!


The Sirens were creatures who lived in the sea and caused death and destruction to those who encountered them. They were half human, half bird, and always described as female. They did not live in the water itself, but on islets and islands. Their method of killing involved singing an enchanting song. This would cause sailors to follow the sound of the song, leading to them walking off the ship or steering the ship into the rocks that the sirens were on.

Sirens | From the blog of Nicholas C. Rossis, author of science fiction, the Pearseus epic fantasy series and children's books

A group of fish-tailed wingless sirens (Latin: “sýrene”) in water, by a ship. Bestiary (Oxford, Bodleian Libraries, Bodl. 764, fol. 74v). Source: Wikipedia

Scylla and Charybdis

Though Scylla’s violence is contrasted with the sirens’ seductive ways by certain classical writers, Scylla and Charybdis lived near the sirens’ domain, were also female, and had some fishlike attributes. In Etruscan civilization before the 6th century BC, Scylla was portrayed as a mermaid-like creature with two tails. Some have argued that the two-tailed Melusine of later European art is traceable to this Etruscan Scylla.

As with the sirens, Scylla and Charybdis appear in the Odyssey. Homer describes two sirens living on a small island that Odysseus had to pass. He saved his crew by plugging their ears with wax, so that they could not hear the sirens’ song. Being curious to hear their enchanting song, he had his sailors tie him to the mast with strict orders not to release him until they were well away from the monsters – a trick that made him the only man to survive their deadly song.


The name ‘Cetus’ (κήτος) was applied to more than one sea monster in Greek mythology. However, the most famous Cetus was the one encountered by Perseus. Cetus was a ferocious whale-like monster. It was released upon the shores of Ethiopia by Poseidon (the god of the sea in Greek mythology). The reason was that the queen of Ethiopia had boasted that her daughter, Andromeda, was more beautiful than the Nereid nymphs.

An oracle told the king and queen of Ethiopia that the only way of resolving the situation was to offer their daughter to the sea monster. Therefore, they tied her to a rock by the shore, waiting for Cetus to devour her. Perseus came to know of this, so he heroically defeated the sea monster. He did this either with his sword or by using Medusa’s head to turn it to stone.

Nowadays, the word κήτος is used in Greek to describe any kind of sea mammal such as whales.


Not all sea monsters in Greek mythology were malevolent. Triton was a sea monster in that he was a bizarre, powerful creature who lived in the sea. The son of Poseidon and Amphitrite, Triton was half man, half fish, essentially a merman (a male mermaid). According to Hesiod, he was the ruler of the depths of the sea and lived at the bottom of the sea in a golden palace. He is usually portrayed as benevolent and helpful to the main character of whatever story he features in.

Triton was not only the son of Poseidon, but also his herald, acting as Poseidon’s messenger. He had a magical conch-shell trumpet, which he could use to calm the waves or to put giants to flight, as they imagined it to be the roar of a dark wild beast. So, while he was a sea monster in his general characteristics, he was a force for good, not evil.


Les Océanides | From the blog of Nicholas C. Rossis, author of science fiction, the Pearseus epic fantasy series and children's books

Les Océanides by Gustave Doré (c. 1860). Image: Wikipedia

Gradually, Triton became pluralized as a group called Oceanids. This group included female oceanids, nereids, and naiads. These daughters of the ‘Old Man of the Sea’ Nereus and the Oceanid Doris, often accompany Poseidon, the god of the sea, and can be friendly and helpful to sailors. While they are not typically depicted with fishtails, the terms “nereid” and “nymph” have also been applied to actual mermaid-like marine creatures purported to exist, from Pliny and onwards. The prophetic sea deity Glaucus was also depicted with a fishtail and sometimes with fins for arms.

This group has nowadays evolved into the mermaids and mermen popularized by Disney, but our ancestors had little doubt of their existence. Pliny the Elder, for example, claimed that a triton (merman) was seen off the coast of Olisipo (present-day Lisbon, Portugal). It bore the physical appearance of the triton, according to a deputation from Lisbon who reported it to Emperor Tiberius. One nereid was sighted earlier on the same (Lisbon) coast. Pliny remarks that contrary to popular notion, the true nereids are not smooth-skinned in their human-like portions, but covered with scales all over the body. Their mournful songs at death have also been heard by the coastal inhabitants. Also, multiple nereids had washed up on the shore according to the governor of Gaul, who informed the late Emperor Augustus about it in a letter.

This notion persisted for a long time. In 1493, sailing off the coast of Hispaniola, Christopher Columbus spotted three sirens or mermaids (Spanish: serenas) which he said were not as beautiful as they are represented, due to some masculine features in their faces. During Henry Hudson’s 1608 voyage in the Arctic Ocean, members of his crew reported sighting a mermaid in the Norwegian or Barents Seas. And Dutch explorer David Danell during his expeditions to Greenland in 1652–54 claimed to have spotted a mermaid with “flowing hair and very beautiful”, though the crew failed to capture it.

It should be noted that a relevant Greek legend was born during the Ottoman Greece period. According to this, Alexander the Great’s sister Thessalonike turned into a mermaid (Greek: γοργόνα) after her death, living in the Aegean. She would ask the sailors on any ship she encountered only one question: “Is King Alexander alive?”,(Greek: “Ζει ο Βασιλεύς Αλέξανδρος;”) to which the correct answer was: “He lives and reigns and conquers the world” (Greek: “Ζει και βασιλεύει και τον κόσμον κυριεύει”). This answer would please her, and she would accordingly calm the waters and bid the ship farewell. Any other answer would enrage her, and she would stir up a terrible storm, dooming the ship and every sailor on board. This legend derives from an Alexander romance entitled the Phylláda tou Megaléxandrou (Φυλλάδα του Μεγαλέξανδρου)first printed in 1680.

The real-life mermaids

People have been trying to find an explanation for this wide range of sea creatures for a long time. Around 546 BC, Milesian philosopher Anaximander postulated that mankind had sprung from an aquatic animal species – a theory that is sometimes called the Aquatic Ape Theory. He thought that humans, who begin life with prolonged infancy, could not have survived otherwise.

There are also naturalist theories on the origins of the mermaid, postulating they derive from sightings of manatees, dugongs, or even seals.

Still another theory, tangentially related to the aforementioned Aquatic Ape Theory, is that the mermaids of folklore were actually human women who trained over time to be skilled divers for things like sponges and spent a lot of time in the sea as a result. One proponent of this theory is British author William Bond, who has written several books about it.

Finally, analytic psychology explains away mermaids as an archetypal symbol of Anima/Animus.

I hope the above has inspired you to include some of these fantastical creatures in your own work! Happy writing!


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