All of ecological nature is woven into food webs and the shorter food chains embedded in webs. Trophic (Gr. trophikos, nourishment) ecology is a synonym for this science, which is the study of 'who eats whom'. Most food webs in the wild are huge, reticulate, and interwoven among species from tiny to large. A famous example is the artistic and ironically named 'Simplified Foodweb for the Northwest Atlantic' by David Lavigne (Figure 1) (http:// www.visualcomplexity.com/vc/project.cfm?id=47 and http://www.fisherycrisis.com/coral7.html).
The first step in the lion's share of research on food webs is simplification. One simplification is to aggregate species that function similarly, for example, green plants, herbivores, predators, etc., and another simplification is focus upon sets of linked species that are particularly interesting or important to an ecological system. Many simplifications yield unbranched food chains.
the proliferation of photosynthetic cyanobacteria in the sea some 3.5 billion years ago, most primary productivity has been the result of oxygenic, photosynthetic, primary producers. These include some bacteria, Archaea, and the more recently evolved algae, lichens, nonvascular plants, and higher plants. The energy source of oxygenic photosynthesizers is sunlight. The two kinds of heterotrophs are biophages (or biotrophs) and saprophages (or saprotrophs). Living organisms are the source of food of the former, and dead organisms are the food of the latter. Biophages include herbivores (animals, fungi, and bacteria that subsist upon live plants), and carnivores (predators, parasites, and diseases of heterotrophs). Detritivore usually applies to organisms consuming dead plant material. Detritivores and saprovores are also called decomposers. Detritivory is important to food webs and food chains because the majority of biomass produced on Earth is not consumed until it is dead. In food chains that do not include primary producers, the basal, source heterotrophs are the producers (see Table 1)
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