being eaten by animals in a living state. In both land and aquatic ecosystems, the role played by detritus is too large to ignore. Aquatic ecosystems In contrast to land ecosystems, dead materials and excreta in aquatic ecosystems are typically transported by water flow; finer particles tend to be transported farther or suspended longer. In freshwater bodies organic material from plants can form a silt known as mulm or humus on the bottom. This material, some called undissolved organic carbon breaks down into dissolved organic carbon and can bond to heavy metal ions via chelation. It can also break down into colored dissolved organic matter such as tannin, a specific form of tannic acid. In saltwater bodies, organic material breaks down and forms a marine snow. This example of detritus commonly consists of organic materials such as dead phytoplankton and zooplankton, the outer walls of diatoms and coccolithophores, dead skin and scales of fish, and fecal pellets. This material will slowly sink to the seafloor, where it makes up the majority of sediment in some areas. Once settled, the material will not only contribute to sediments but will help to feed different species of detritivore, organisms which feed on detritus, such as annelid worms and sea cucumbers, to name a few. The exact composition of this detritus varies based on location and time of year, as it is very closely tied to primary production. Terrestrial ecosystems Detritus occurs in a variety of terrestrial habitats including forest, chaparral and grassland. In forests, the detritus is typically dominated by leaf, twig, and bacteria litter as measured by biomass dominance. This plant litter provides important cover for seedling protection as well as cover for a variety of arthropods, reptiles and amphibians. Some insect larvae feed on the detritus. Fungi and bacteria continue the decomposition process after grazers have consumed larger elements of the organic materials, and animal trampling has assisted in mechanically breaking down organic matter. At the later stages of decomposition, mesophilic micro-organisms decompose residual detritus, generating heat from exothermic processes; such heat generation is associated with the well known phenomenon of the elevated temperature of composting. Consumers There is an extremely large number of detritus feeders in water. After all, a large quantity of material is carried in by water currents. Even if an organism stays in a fixed position, as long as it has a system for filtering water, it