Feeding behavior and growth of sea urchins was studied with a population of juvenile Tripneustes ventricosus from a seagrass (Thalassia testudinum) stand in Bermuda. Feeding and foraging patterns, preferences and daily consumption rates were determined in field experiments and related to vegetational parameters of the turtle grass community. Although the results confirm that the direct impact of grazing on productive tissue is almost negligible they suggest a revision of the role that sea urchins and other herbivores play in seagrass communities. Their striking inability to efficiently exploit the rich nutritional potential and productivity of seagrasses is interpreted as an evolutionary strategy of maintaining imperfectness on the species level for the benefit of the community. The distinct mode of foraging and selective grazing observed in this study serves as resource management, ensuring persistence and predictibility for both the consumer and the producer. The observed pattern, however, also allows an optimization of feeding and net energy gain through its time-minimizing and energy-maximizing character. Sea urchins grazing at moderate density in seagrass beds function as a community stabilizing factor rather than bearing the potential hazard of exploitation.