Physiological ecology
  There is not much in the scientific literature on physiological ecology of west-coast sand dollars.
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Research study 1

A study on pigments in sand dollars at La Jolla, California shows that Dendraster excentricus has 2 water-soluble purple pigments and 2 echinochrome-like ether-soluble pigments.  The function of the pigments is not known.  Goodwin & Fox 1955 Experientia 11: 270.

NOTE  a deeper-dwelling (15-20m) species D. laevis contains only a single water-soluble green pigment

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