Stichopus does not. Even though the former were washed and scrubbed with the hand at the time of collection it is clear that the specific activity of their body wall, which includes the skin, is the higher. That this is due to surface contam- ination is further substantlated by the greater individual differences in the specific activity of the body wall of H.atra. Table 19 - COMPARISON OF RADIOACTIVITY OF TWO SPECIES OF SEA CUCUMBERS COLLECTED AT AARAANBIRU POST SHOT Thousands of d/m/g Wet Sample Holothuria atra Body wall 140 230 Gut & contents Body wall Gut & contents 4600 1100 8.5 5.4 64 6800 6.1 5.4 3600 110 4600 6.5 5200 17 Ave. ~Stichopus sp. 5800 7.2 2600 5800 4400 4200 The degree to which the food habit affects the specific activity of the digestive tract and contents is found in 4 come parison of the viscera of a pistol shrimp (Crangon sp.) and a blue-green alga (Lyngbia sp.), which are intimately related ecologically. Two specimens of shrimp were found, one at Rig- {141i and one at Runit, living in a completely closed cylinder of the living algae. The cylinders had to be torn open in A similar if not the same assoc- order to remove the shrimp. {ation was reported by Taylor with specimens from Rongerik and Bikini Atolls in the Marshall Islands .© least in part, This shrimp feeds at upon the algae in which it lives. - 102 “ It may how-

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