The astrological sign of Cancer and the Great Mother are both represented by the crab.
Psychological / Emotional Perspective:
Because the crab has a hard shell and is thus self-protective, in dreams this quality can be highlighted. When someone is ‘crabby’they are irritable or morose. The crab apple is small and sour and therefore has this same connotation.
Everyday Material Aspects:
A crab appearing in a dream can indicate mothering, particularly of the ‘smother love’type, but can also be the qualities of unreliability and self-interest. The crab can also, because of the way it moves, denote deviousness.
Gender / Specific Meanings:
In a woman’s dream the crab will often represent the different aspects of the three-faceted Moon goddess, maid, mother and crone. In a man’s dream it is more likely to suggest the ‘smother mother’.