Hematophagy is the practice by certain animals of feeding on blood. Since blood is a fluid tissue rich in nutritious proteins and lipids that can be taken without great effort, hematophagy is a preferred form of feeding for many small animals, such as worms and arthropods. Some intestinal nematodes, such as Ancylostomatids, feed on blood extracted from the capillaries of the gut, and about 75 percent of all species of leeches, a free-living worm, are hematophagous. Some fish, such as lampreys and candirus, and mammals, especially the vampire bats, and birds, such as the vampire finches, hood mockingbirds, the Tristan thrush, and oxpeckers also practise hematophagy.
