On the Octopus from "Understanding Northwest Coast Art" by Cheryl Shearar:
Octopus is common in Shamanic art, undoubtedly because of its amazing transformation abilities. It is also a crest in some regions―among the Tsimshian Eagle clan, for example. Among the Haida, Octopus features in legend and myth, but is not a crest.
Myths speak of a giant devilfish monster who occasionally devours canoes and sometimes entire villages. Octopus is a powerful sea spirit helper, often shown in complex compositions involving other creatures. In some tribal cultures, eight is considered a magic and auspicious number, which adds to the appeal and power of Octopus. Octopus is a servant of Kumugwe, chief of the undersea world, and is also a symbol of great wealth in Kwakwaka'wakw mythology.