Coenzyme Q (Q) regulates aging in Caenorhabditis elegans, and its deficiency leads to a variety of pathologies in humans. We used a coq-8 deleted strain to study the role of Q in C. elegans development and how it influences life span. Endogenous Q(9) content of coq-8(ok840) knockouts was demonstrated to be about 7% of that found in the wild-type, indicating the basal biosynthesis rate is reduced in this strain. Knockouts abnormally developed both gonads and hypodermis, showed reduced fertility and shortened life span, and this was partially recovered by ingestion of exogenous Q. Knockouts produced embryos that showed arrested development at the time of initial expression of coq-8 in embryo. Uridine, whose biosynthesis depends on mitochondrial Q, improved both egg production and progeny under Q-rich dietary conditions. COQ-8 is a candidate protein for post-translational regulation of Q biosynthesis rate and its expression correlates with Q content during the life cycle in C. elegans. We show for the first time that a critical level of Q is necessary to support embryo development and fertility in C. elegans. These results suggest that extra-mitochondrial function of Q is a key factor linking development and bioenergetics in C. elegans.