The sustainable utilization of commercially important crabs in aquaculture and fisheries requires a sound resource management, and this must be based on solid knowledge of the basic biology of the Decapoda. Most crab species pass through a complex life cycle including a development through meroplanktonic larval stages. Since the larvae differ in all major morphological, physiological and ecological characteristics from the conspecific juvenile and adult life-history stages, we cannot easily extrapolate our knowledge of basic crab biology. The larval phase is, in general, physiologically much more sensitive, and is therefore considered as a bottleneck which is critical for the survival, growth and reproductive success of a crab population, regardless whether artificially cultivated or fished in the natural habitat. While studies of species-specific traits of commercially exploited crab species always remain an important task, many principal aspects of the larval biology can be extrapolated with satisfactory accuracy from model species, which are not necessarily commercially important. Model species should be easily available, easy to handle, and have high survival in laboratory culture. Moreover, some specific traits may be differentially valuable for various experimental approaches and contexts. A high number of larval stages, for instance, helps to analyze growth patterns in extended series of successive stages, or indicate long-term effects of variation in environmental conditions such as larval nutrition or physical factors. In other model species, few larval stages with long durations are advantageous for high-resolution studies of growth or physiological changes within individual moulting cycles. In biochemical and physiological studies, large larval size and/or high fecundity are further valuable traits. As most commercially important crab species have a coastal or estuarine distribution, interrelationships between ontogenetic changes in larval ecology, transport patterns, and the physiological basis of tolerance of variations in salinity, temperature or food availability should be studied in model species with similar life history strategies. Since those prerequisites do not co-occur in a single species, there is no ideal model for all different questions. Moreover, information transfers from models to species that are utilized in aquaculture or fisheries remain to be checked in selective (i.e. limited) comparative studies.