Most studies of energetics in marine filter feeders have focused on animals living in steady state food conditions. However, copepods experience highly variable access to food because of food patchiness and behavioural avoidance of predators. For small copepods this is especially important since they lack the potential of energy storage, e.g. in the form of lipids. After a period of food deprivation Acartia tonsa show a compensatory increase in ingestion rate, but only temporarily and on the time scale of the gut filling time. The copepods are able to compensate for the lacking input of food. On the other hand, longer periods of starvation (6-14h) induce elevated ingestion rates that lasts longer than gut filling time. Under these circumstances other energetic factors influence the ingestion rate. Consequently, the energetics of the copepods are highly variable in a patchy food environment.