The Detritus-Based Trophic System 435 



TABLE 11-7 



Division of Energetic Activity According to Trophic 

 Function (% of activity) Assigned to the Various 

 Invertebrate Groups. 



available, mineral matter. O'Connor (1967) found fungi in greater pro- 

 portion in the gut than in the available substrate for two of three enchy- 

 traeid species examined, while the third species showed no selectivity. 

 Dash and Cragg (1972) found that boreal woodland Enchytraeidae were 

 attracted to fungal baits placed on the soil surface. Nielsen (1962) exam- 

 ined the digestive enzymes of four species of Enchytraeidae, including 

 one species of Mesenchytraeus, and concluded that they are unable to 

 break down the complex structural polysaccharides of higher plants. 

 Thus, it appears that Enchytraeidae are primarily microbivores, selec- 

 tively ingesting fungi and also feeding upon bacteria and algae ingested 

 with dead organic matter. 



Most investigators emphasize the importance of fungal hyphae in 

 the diet of Collembola (Peterson 1971); however, evidence from gut con- 

 tents (Bodvarsson 1970), feeding preference and growth rate (Addison 

 1977), and digestive enzymes (Zinkler 1969) of Collembola of the genus 

 Folsomia indicate that they feed directly upon dead organic matter. Since 

 Folsomia quadrioculata and F. diplophthalma, together, constitute 70% 



