INTESTINAL ABSORPTION AND TRANSPORT IN THYONE. I. BIOLOGICAL ASPECTS

¹ Marine Biological Laboratory, Woods Hole, Massachusetts and Department of Physiology, Rutgers University, New Brunswick, New Jersey 08903

Several investigators have proposed that the transport of nutrients from the intestine to the tissues of holothurians is mediated by wandering coelomocytes. These and other authors have also implied that hemal system is a functional circulatory system in adult holothurians. On the basis of the present studies, these views are rejected. Evidence for the direct absorption of glucose by the intestinal epithelium and its transmural transport into the perivisceral fluid is presented. The perivisceral fluid is the main circulatory medium for gaseous exchange and nutrient transport to the internal tissues. Ecological, anatomical, and histological information pertinent to the study of intestinal transport mechanisms is presented. In addition to digestive and absorptive functions, the intestinal tissue serves as the storage site for relatively large quantities of carbohydrate and lipid reserves.

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