Hemolymph of the animal's body and surrounds all cells. It contains hemocyanin, a copper-based protein that turns blue when oxygenated, instead of the iron-based hemoglobin in red blood cells found in vertebrates, thus giving hemolymph a blue-green color rather than the red color of vertebrate blood. When not oxygenated, hemolymph quickly loses its color and appears grey. The hemolymph of lower arthropods, including most insects, is not used for oxygen transport because these animals respirate through other means, such as tracheas, but it does contain nutrients such as proteins and sugars. Muscular movements by the animal during locomotion can facilitate hemolymph
Red blood cell synthesised by the kidney. Just before and after leaving the bone marrow, the developing cells are known as reticulocytes; these constitute about 1% of circulating red blood cells. The functional lifetime of a red blood cell is about 100–120 days, during which time the red blood cells are continually moved by the blood flow push (in arteries), pull (in veins) and a combination of the two as they squeeze through microvessels such as capillaries. They are also recycled in the bone marrow. The aging red blood cell undergoes changes in its plasma membrane, making it susceptible to selective recognition by