Absorption of Calcium through Digestive Tract in Sea Urchin

Abstract

Absorption of calcium from food was investigated in sea urchin Hemicentrotus Pulcherrimus by two methods: the use of Cr₂O₃ or labelled calcium-⁴⁵CaCl₂. The test foods were agar film containing laminarian seaweed powder and these added with Cr₂O₃ or ⁴⁵CaCl₂. The examinations were carried out at water temperature of 19°C in May and June.
Based on the observed concentration of index substances in test food and faeces, calculated absorption rates of calcium from test food in gut were about 30% in both experiments. It was confirmed that the coelomic fluid is an important route for transport of calcium.