Sand Dollar: A Weight Belt for the Juvenile

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Science  06 Jul 1973:
Vol. 181, Issue 4094, pp. 73-74
DOI: 10.1126/science.181.4094.73


Juvenile sand dollars (Dendraster excentricus) selectively ingest heavy sand grains from the substrate and store them in an intestinal diverticulum which may function as a weight belt, assisting the young animal to remain in the shifting sandy environment. The sand disappears from the diverticulum when the animal reaches the length of 30 millimeters.