Absorption of labelled calcium-45Ca by prawn from sea water.

Abstract

In connection with the previous study of the mineral requirements of prawn, Penaeus japonicus, the absorption of radioactive calcium-45Ca from surrounding sea water by the prawn fed on a diet without supplemental calcium was compared with that of the prawn fed on a calcium-supplemented diet. The surrounding sea water was prepared to contain labelled calcium-45Ca-CaCl2. The prawn were first fed on each test diet in ordinary sea water, and one hour after the final mealtime were transferred to sea water in which 45Ca-CaCl2 was dissolved. One, four, and twentythree hours later, the prawn were analyzed for the radioactivity incorporated into their bodies. The radioactivity of 45Ca accumulated in the prawn gradually increased with the lapse of time, and the group fed on the diet without supplemental calcium exhibited faster absorption and higher activity of 45Ca than the group fed on the diet with calcium.