A major area of interest concerns the production of greenhouse gases from the gut-dwelling microbial communities associated with earthworms [3][13][14]. One recent study investigated how the size of the earthworm affects the emission of N2O [3]. They found that all the small species they used for their study (Amynthas gracilis, Pontoscolex corethrurus, Eudrilus eugeniae, Perionyx excavatus, Dichogaster annae, and other Dichogaster spp.) and one large species (Rhinodrilus alatus) in this study did emit N2O. One large species (Glossoscolex paulistus) did not produce N2O though it was capable of denitrification. They found similar narG, nirK, and nosZ gene sequences in the guts of the non-N2O-producing large species as was in the soil, but the sequences in the guts of the small N2O-producing species were different from the soil sequences and had more Rhizobiales sequences. This led to the conclusion that Rhizobiales species are associated with the emission of N2O, and that a wide range of earthworm physiologies are conducive to this process.