Lymph Hearts

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Lymph Hearts are organs found in lungfishes, all amphibians, reptiles and flightless birds. They function as small pumps that pump lymph (fluid, proteins and ions) that has leaked out of the circulatory system, back into the circulatory system. These hearts vary in size from microscopic in lungfish to an estimated 20 liters capacity in some of the largest dinosaurs. In frogs and turtles they pump at rates higher than the blood heart and the volumes pumped are quite remarkable. In toads and frogs this volume can amount to about 1/50th of the output of the blood heart. In flightless (ratite) birds the lymph heart function is less clear and the two almond sized hearts located near the spinal column close to the hip joint are thought to be involved in inflating and deflating the phallus with lymph which is of a significant size in both sexes of emus and ostriches.