ABSTRACT
Shrinkage in response to starvation or low food has been reported for sea urchins in a variety of field and laboratory studies during the past 35 years. Decreases in test diameter have been reported for Strongylocentrotus purpuratus (Ebert 1967, 1968; Pearse & Pearse 1975), Paracentrotus lividus (Régis 1979), Diadema antillarum (Levitan 1988, 1989), and Heliocidaris erythrogramma (Constable 1993). The reported magnitude of decrease varies from less than 1 mm (Pearse & Pearse 1975) to 7 mm (Levitan 1989). Small changes of less than a millimeter in ambital diameter could result from tightening of sutures that are relatively open during rapid growth and is the mechanism proposed by Pearse & Pearse (1975) and Constable (1993); no resorption of calcite would be required. Large decreases, on the other hand, would require resorption of skeletal calcite.
