Chapter 11 Decomposers and Detritivores Introduction When plants and animals die, their bodies become resources for other organisms. Of course, in a sense, most consumers live on dead material – the carnivore catches and kills its prey, and the living leaf taken by a herbivore is dead by the time digestion starts. | I .J Chapter 11 Decomposers and Detritivores saprotrophs detritivores and decomposers. Introduction When plants and animals die their bodies become resources for other organisms. Of course in a sense most consumers live on dead material - the carnivore catches and kills its prey and the living leaf taken by a herbivore is dead by the time digestion starts. The critical distinction between the organisms in this chapter and herbivores carnivores and parasites is that the latter all directly affect the rate at which their resources are produced. Whether it is lions eating gazelles gazelles eating grass or grass parasitized by a rust fungus the act of taking the resource harms the resource s ability to regenerate new resource more gazelles or grass leaves . In contrast with these groups saprotrophs organisms that make use of dead organic matter do not control the rate at which their resources are made available or regenerate they are dependent on the rate at which some other force senescence illness fighting the shedding of leaves by trees releases the resource on which they live. Exceptions exist among necrotrophic parasites see Chapter 12 that kill and then continue to extract resources from the dead host. Thus the fungus Botrytis cinerea attacks living bean leaves but continues this attack after the host s death. Similarly maggots of the sheep blowfly Lucilia cuprina may parasitize and kill their host whereupon they continue to feed on the corpse. In these cases the saprotroph can be said to have a measure of control over the supply of its food resource. We distinguish two groups of saprotrophs decomposers bacteria and fungi and detritivores animal consumers of dead matter . Pimm 1982 described the relationship that generally exists between decomposers or detritivores and their food as donor controlled the donor prey . dead organic matter controls the density of the recipient predator . decomposer or detritivore but not the reverse. This . do not .
