Camels have oval-shaped red blood cells that keep flowing even when severe dehydration thickens their blood.

The unique physiology of the dromedary camel (Camelus dromedarius) is a marvel of evolutionary adaptation. Unlike the circular, biconcave red blood cells found in humans and most other mammals, camel erythrocytes are oval-shaped. This elliptical structure allows the cells to remain oriented in the direction of blood flow, which minimizes resistance and prevents clumping when the blood becomes viscous due to extreme water loss.Research published in the Journal of Comparative Physiology highlights that camels can lose up to 30% of their body weight in water without suffering heart failure. In most mammals, such severe dehydration would cause the blood to become too thick to circulate through the capillaries. The camel's oval cells are remarkably small and flexible, enabling them to navigate the narrowest vessels even when the animal is severely dehydrated.Furthermore, these cells possess highly elastic membranes composed of unique proteins and lipids. When a thirsty camel finds water, it can drink up to 30 gallons (113 liters) in just 13 minutes. This rapid intake of water would cause normal mammalian red blood cells to swell and burst through osmotic shock. However, the camel's cells can expand to more than double their original volume to accommodate the sudden influx of fluid.This adaptation was first documented in detail by researchers such as Knut Schmidt-Nielsen, who spent decades studying desert animals. His findings showed that the camel's ability to regulate its internal temperature and maintain blood circulation is key to its survival in temperatures exceeding 120°F (49°C). The oval shape is not just a curiosity but a specialized biological tool for surviving one of the harshest environments on Earth.