In Melanesia there is a belief in the tamaniu or atai which is an animal counterpart to a person with which his life is bound up.
Nature
The tamaniu like the atai has an objective and material existence. This creature is corporeal, can understand human speech, and shares the same soul as its master, leading to legends which have many characteristics typical of shapeshifter tales, such as any death or injury affecting both forms at once.
Description
The tamaniu can be an eel, a shark, a lizard, or some other creature.
Powers
When its owner wishes to injure anyone he sends his familiar to do so ; if an eel it would tear or bite, if a shark probably swallow him. If the owner falls ill, he examines his familiar to discover what is wrong. The imps or familiars of witches embody the same idea.
Story
Dr. W. H. R. Rivers quotes the case of a man whose tamaniu was a lizard. "The owner was blind and asked a friend to help him with the ceremony of examination. He told his friend to go and see the animal, using the words " Look at me," referring to the lizard as himself. The man went alone to the banyan tree where the lizard was to be found, but when he came there he was too frightened to call upon the animal. He was sent a second time in the company of the sick man's son and others, and when they reached the tree the man called out the lizard's name, Rosasangwowut, and the tamaniu appeared. It was a very large animal, larger than the ordinary lizards in Mota. It appeared to be sluggish and walked as a sick man would walk. The blind man's son then asked the tamaniu if it was ill and the creature nodded its head and moved slowly back to the tree. They went back and told the man that his familiar was ill, and soon afterwards he died. At the same time the banyan tree fell, which was taken as a sign that the tamaniu died too. This is an uncanny story which brings out strongly the psychic connection between the man and his representative animal."(1)
Source
^ " Totemism in Polynesia and Melanesia " in " Journal of the Royal Anthropological Institute," 1909, Vol. XXXIX, p. 177.