Comparison of erythrocyte osmotic fragility among ectotherms and endotherms at three temperatures

1. Comparison of erythrocyte osmotic fragility (EOF) between various ectotherms and endotherms was investigated at 5, 25, and 38°C. 2. We hypothesized that ectotherms might possess erythrocytes whose osmotic fragility would be less affected by temperature than those of endotherms. 3. Ectotherm erythrocytes were much more osmotically resistant than those of endotherms. 4. The EOF of ectotherms and endotherms showed similar responses to temperature. 5. It does not appear that the osmotic fragility of erythrocytes from ectotherms in this study are adapted to be less affected by temperature than those of endotherms. The highly osmotic resistant erythrocytes of ectotherms may alleviate the need for further adaptation for osmotic resistance.