Supernatural Friday: Are Those Kelpies and Water Horses Swimming in Your Pool?

“Riding upon the back of a waterhorse - what mortal had ever stayed in such a seat for so long? On a horse made of cold currents and liquid convergences, jests and trickery - pressed against a hide like the burnished sea of midnight, thing look different to the rider.”
― Cecilia Dart-Thornton, The Battleof Evernight

Kelpie, or water kelpie, is the Scots name given to a water being inhabiting the lochs and pools of Scotland. Sometimes said to appear as a horse, sometimes like a giant snake-like monster with horse’s head, it can also assume human form. Some accounts state that the kelpie retains its hooves when appearing as a human, leading to its association with the Christian idea of Satan. The etymology of the Scots word kelpie is uncertain, but it may be derived from the Gaelic calpa or cailpeach, meaning "heifer" or "colt.”  The term kelpie to a wide variety of mythical creatures. Counterparts in some regions of Scotland include the shoopiltee and nuggle of Shetland and the tangie of Orkney; in other parts of the United Kingdom they include the Welsh ceffyl dŵr and the Manx cabbyl-ushtey.

Many bodies of water in Scotland have kelpie story in connection, but the most famous is that of Loch Ness, and it parallels to the general Germanic neck and the Scandinavian bäckahäst (Shapeshifting water spirits in Germanic mythology and folklore who usually appeared in forms of other creatures.).  More widely, the wihwin (Malevolent water spirit of Central America, particularly associated with the Mosquito tribe. The horse-shaped monster has "jaws fenced round with horrid teeth", which it uses to consume humans and other prey it finds on its nocturnal hunts.) of Central America and the Australian bunyip (A large mythical creature from Aboriginal mythology, said to lurk in swamps, billabongs, creeks, riverbeds, and waterholes.) have been seen as counterparts.

The origin of the belief in malevolent water horses has been proposed as originating in human sacrifices once made to appease gods associated with water. The association with horses may have its roots in horse sacrifices performed in ancient Scandinavia There are narratives about the kelpie that served a practical purpose in keeping children away from dangerous stretches of water, and warning young women to be wary of handsome strangers. The kelpie is usually described as a powerful and beautiful black horse inhabiting the deep pools of rivers and streams of Scotland, preying on any humans it encounters. One of the water-kelpie's common identifying characteristics is that its hooves are reversed as compared to those of a normal horse, a trait also shared by the nykur of Iceland. An Aberdeenshire variation portrays the kelpie as a horse with a mane of serpents, whereas the resident equine spirit of the River Spey was white and could entice victims onto its back by singing. Kelpies take their victims into the water, devour them, and throw the entrails to the water's edge. In its equine form the kelpie is able to extend the length of its back to carry many riders together into the depths, a common theme in the tales is of several children clambering onto the creature's back while one remains on the shore. Usually a little boy, he then pets the horse but his hand sticks to its neck. In some variations the lad cuts off his fingers or hand to free himself; he survives but the other children are carried off and drowned, with only some of their entrails being found later.

A tale set at Sunart in the Highlands tells of nine children lost, of whom only the innards of one are recovered. The surviving boy is again saved by cutting off his finger, and additional information is given that he had a Bible in his pocket. Some this creature responsible to have been a water horse rather than a kelpie, and the tale "obviously a pious fraud to keep children from wandering on Sundays.”
When a kelpie appeared in its equine persona without any tack, it could be captured using a halter stamped with the sign of a cross, and its strength could then be harnessed in tasks such as the transportation of heavy mill stones. A bridle taken from a kelpie was endowed with magical properties, and if brandished towards someone, was able to transform that person into a horse or pony.

A kelpie can be killed by being shot with a silver bullet, after which it is seen to consist of nothing more than turf and a soft mass like jelly-fish (I can see this, as like the werewolf or other shapeshifters that can be killed by silver too.). When a blacksmith's family was being frightened by the repeated appearances of a water kelpie at their summer cottage, the blacksmith managed to render it into a "heap of starch, or something like it" by penetrating the spirit's flanks with two sharp iron spears that had been heated in a fire.

There is a folk tale from Barra tells of a lonely kelpie that transforms itself into a handsome young man to woo a pretty young girl it was determined to take for its wife. But the girl recognizes the young man as a kelpie and removes his silver necklace (his bridle) while he sleeps. The kelpie immediately reverts to its equine form, and the girl takes it home to her father's farm, where it is put to work for a year. At the end of that time the girl rides the kelpie to consult a wise man, who tells her to return the silver necklace. Once again transformed into the handsome young man she had first met the wise man asks the kelpie whether if given the choice it would choose to be a kelpie or a mortal. The kelpie in turn asks the girl whether, if he were a man, she would agree to be his wife. She confirms that she would, after which the kelpie chooses to become a mortal man, and the pair is married.