Most parasites are obligate i.e., they are unable to survive apart from their hosts. Often this is because in the course of evolution they have lost various of the organs necessary to live as independent units. Many parasites also have extremely specialized reproductive systems and complex life cycles, involving more than one host. Some higher plants and animals are parasitic, e.g., the dodders (vines of the morning glory family) and the cuckoo and the cowbird, which lay their eggs in the nests of other birds.
An epiphyte , or air plant, although it lives in association with another plant, is not a parasite. Organisms that obtain their nourishment from dead organic matter, e.g., mushrooms, are called saprophytes or saprobes. See also symbiosis .
See R. Drisdelle, Parasites (2010).
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
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