Role of the Gut as a Nutrient-Storage Organ in the Purple Sea Urchin (Strongylocentrotus purpuratus)

Abstract

The effect of feeding and starvation on the lipid, carbohydrate, and protein content of the gut and gonad and upon the lipid and carbohydrate content of the body fluid of post-spawning purple sea urchins were studied. Starvation had no demonstrable effect on gonad size. The protein content of the gonad (in % dry weight) increased while total lipid, neutral lipid, and carbohydrate decreased in both field and laboratory animals. The water content of the gut remained the same. The relative size of the gut decreased with starvation. The decrease in total lipid content could be attributed to a change in the neutral lipid fraction, since the polar lipid fraction remained constant. Carbohydrate, present in small amounts in the gut, also declined with starvation. Feeding arrested the decrease in relative size of the gut and its content of total lipid, neutral lipid, and carbohydrate. The protein and polar lipid content of the gut varied comparatively little with starvation and feeding. Decrease in the size of the gut with starvation is therefore attributable mainly to utilization of neutral fat. The level of total carbohydrate, D-glucose, and total Upid in the body fluid decreased with starvation and increased with feeding.