The energetic importance of the galatheid crab, Pleuroncodes planipes, was examined in the California Current off Baja California during April 1973. Respiration of Pleuroncodes ranged from 132 to 408??l O2?h?1, which was equivalent to 404–728??l O2?g ash free dry wt?1 h?1. Analyses of Pleuroncodes revealed that water, ash, protein, lipid, and chitin constituted 84, 7, 3.5, 0.7, and 2.8% of the total weight, respectively. These analyses give a mean caloric content of 1700?±?430?cal. Pleuroncodes is a dominant functional component of the upwelling ecosystem in the California current and is comparable to the anchovy, Engraulis ringens, in the Peru upwelling ecosystem.