A characteristic feature of fungal hypha is the presence of large number of nuclei in a common cytoplasmic environment. Where it has been examined, the coenocytic mycelium is commonly heterokaryotic. The nuclei cooperate, compete or combat. It is proposed that in addition to their classical role in heredity, supernumerary nuclei in filamentous fungi serve as store house for nitrogen and phosphorus in the form of DNA which is degraded by regulated autophagy. The breakdown products recycled, giving hyphal tips the capability of persistent extension and foraging in new areas.