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Starfish show how ancient the immune system is
There are two evenly important aspects of the immune system : Innate immunity and adaptive exemption . The inborn immune system consists of electric cell and protein that are always quick to fight microorganisms at the land site of infection ; the adaptive immune system gets called into action when pathogen bypass the innate defenders .
invertebrate — animals without a rachis — generally miss the adaptive exemption that vertebrates have . But in the late nineteenth century , Russian life scientist Russian life scientist Élie Metchnikoff discovered that invertebrate do have an congenital resistant system .
One even in December 1882 , Metchnikoff pierce a starfish larva with a blush wine spikelet . When he examined it the next day , he discovered a multitude of tiny cells trying to engulf the thorn ( an inborn immune process called phagocytosis ) .
Importantly , the sea star has remained largely unchanged since it evolved some 500 million years ago , long before craniate come up onto the aspect , suggesting that the innate resistant system has very ancient roots .
