ABSTRACT
Many people think a lichen is a plant, but it’s actually a “composite organism” made from members of two species—one a fungus and the other algae or bacteria (or rarely, both). The fungus provides support and structure for the algae to grow, while the algae or bacteria use photosynthesis to convert sunlight into nutrients, which feeds the fungus. Chimerism usually occurs via egg fusion— but there's another way people (and some animals) may become chimeric: organ transplants. If an individual receives a kidney, liver, or heart from a donor, for instance, the cells in those organs will have a different genome. If the transplanted tissue is bone marrow, it can even change the recipient's blood type. The organisms that make up the Portuguese man-of-war are called zooids, and each type of zooid has its own job. There are zooids for floatation, captur-ing prey, digesting food, and reproduction.
