CALCIUM-METABOLISM IN OLIVE RIDLEY TURTLE EGGS DURING EMBRYONIC-DEVELOPMENT

Analyses of calcium, magnesium, sulphur, potassium and phosphorus cont ent of the eggshell, yolk-albumen and embryos of olive ridley turtle, Lepidochelys olivacea, have been carried out at various stages of embr yonic development. Calcium is the major inorganic constituent in the e gg (shell and yolk-albumen) and embryos. Other elements are present ei ther in trace or in minute trace amounts. The egg contents (yolk and a lbumen) provide only 40% of the embryonic calcium requirement of the h atchling. The remaining 60% is provided by the eggshell. The eggshell also undergoes a similar reduction in its calcium content from laying to hatching. Elements other than calcium present in the yolk-albumen a re sufficient for normal embryonic development. The movement of calciu m from the eggshell to the embryo starts at about the 401th day of dev elopment at 29.5 degrees C. Birds, turtles and crocodiles use their eg gshell as the secondary source of embryonic calcium requirement. This dependence on the eggshell varies in different groups which is highest in birds and lowest in crocodiles. (C) 1998 Elsevier Science Inc. All rights reserved.