Deriving from the Gaelic word murúch the Merrow is the Irish equivalent of the mermaid and mermen of other traditions. These beings are said to appear as human from the waist up but have the body of a fish from the waist down. They have a gentle, modest, affectionate and benevolent disposition.
There are other names pertaining to them in Gaelic - Muir-gheilt, Samhghubha, Muidhuachán, and Suire. They would seem to have been around for millenia because according to the bardic chroniclers, when the Milesians first landed on Irish shores the Suire, or sea-nymphs, played around them on their passage.
The merrow were capable of attachment to human beings and there are reports of them inter-marrying and living among humans for many years. However usually they eventually return to their former homes beneath the sea.
Merrow-maidens are reputed to lure young men to follow them beneath the waves where afterwards they live in an enchanted state. Merrows wear a special hat called a cohuleen druith which enables them to dive beneath the waves, if they lose this cap it is said they have no power to return beneath the water. Sometimes they are said to leave their outer skins behind, to assume others more magical and beautiful. The merrow has soft white webs between her fingers, she is often seen with a comb parting her long green hair on either side. Merrow music is often heard coming from beneath the waves.
An old tract found in the Book of Lecain states that a king of the Fomorians, when sailing over the Ictean sea, had been enchanted by the music of mermaids until he came within reach of these sirens .... then they tore his limbs asunder and scattered them on the sea.
From Dr. O'Donovan's Annals of the Four Masters - Entered in the year 887 ad. there is a curious tale of a mermaid cast on the Scottish coast - Alba - She was 195 feet in length and had hair 18 feet long, her fingers were 7 feet long as was her nose, while she was as white as a swan.
Most of the stories are about female beings however there are some about mer-men who capture sailors and keep them in cages under the sea.
Source: O'Hanlon, John - Irish folklore: Traditions and Superstitions of the Country. first published 1870. republished by EP Publishing Ltd., 1973.
picture source: Arthur Rackham
Stories, Myths and Legends associated with the Merrow