13 water, or radionuclides may be adsorbed on the surface of the animal. Although adsorption is an important means of contami- nation of organisms by fresh fallout, it is probably no longer important at Bikini, where the last significant fallout occurred in 1958. The astronomically large surface area presented by the masses of branching corals and their associated flora and fauna must have removed, from the water, all adsorbable radionuclides not already removed by the plankton soon after fallout. The land organisms contain primarily the long-lived fission products 137 og and 905, and, as expected, these radionuclides are found associated with those tissues or organs which contain potassium and calcium, respectively, since cesium and potassium behave similarly in metabolism, as do strontium and calcium. there are quantitative and qualitative differences in radionuclide content of organisms associated with feeding habit. 7 The goatfish, a bottom-feeding carnivore, contains more 6000 and 20754 than the convict surgeonfish, a grazing herbivore, or the mullet, a plankton feeder (Tables 2 and 2). Higher order 4 60 carnivores, the grouper and ulua, also contain more Co and 207 34 (Table 4) than the convict surgeonfish; however, the differences may be associated with age as well as with feeding habit. The smaller, and presumably younger, reef fish of a species contain less 90 Sr than the larger fish of the same species