A tortoise's heart can change its physical shape to survive for months without oxygen.

Species like the desert tortoise and the western painted turtle are masters of anaerobic survival. During hibernation or in deep burrows, oxygen levels can drop to near zero, a state known as anoxia. To cope, the heart undergoes a morphological change, shifting from a pointed spade-like appearance to a more spherical, boxy shape. This change reduces the workload on the heart muscle while maintaining the blood pressure needed to fuel the brain.Research published in journals like the Journal of Experimental Biology highlights how these reptiles can survive for up to four months without breathing. They rely on massive stores of glycogen in their livers and hearts to produce energy without oxygen. Additionally, they use their shells and skeletons to release calcium and magnesium carbonates. these minerals neutralize the buildup of lactic acid in their blood, preventing it from becoming toxic.Scientists at institutions like the University of Manchester have studied these mechanisms to better understand human heart health. By observing how the tortoise heart resists damage during low-oxygen states, researchers hope to develop new treatments for heart attacks and organ transplants. This unique biological flexibility ensures that the most critical organ, the brain, remains protected even when the rest of the body slows down to a near-halt.