Earthworms play a major role in the biogeochemical cycling of carbon and nitrogen through their bioturbation activity and cast production. Thus, they affect soil greenhouse gas emissions mainly, N2O and CO2 as well as carbon sequestration through their influence on soil organic matter protection processes. However, earthworm casts exhibit differents physical, chemical and biological characteristics, even when the species belong to the same ecological category. Animal functional traits were recently used in ecology approach to study invertebrates’ effect on ecosystem function. These traits drive the response of organisms at individual level to environmental changes and their effects on ecological processes. The objective of this work was to investigate the role of earthworm functional traits in organic matter dynamics. We performed a laboratory experiment to assess the effect of morphological, anatomical, physiological, and behavioral traits of 9 temperate earthworm species on the nature, protection, and molecular chemical composition of organic matter from earthworm casts. We characterized the particular organic matter (POM) and mineral-associated organic matter (MAO)M through physical fractionation. The nature and molecular chemical composition of organic matter in casts was determined from elementary, isotopic and mid-infrared spectra analyses. results showed a strong correlation between physical and chemical parameters (i.e., dissolved organic carbon, particulate organic matter, total carbon, C/N ratio and nitrogen contents) and the size of the earthworm, gizzard, pharynx, pigmentation, low dissepiment and selection of organic matter. We conclude that earthworm traits can be used to predict their effect on organic matter dynamic.