DO CEPHALOPODS AND LARVAE OF OTHER TAXA GROW ASYMPTOTICALLY

Species that reach the end of a life-history stage (transform) at relatively fixed sizes may often grow nonasymptotically before transforming. Many species of squid and at least some larval frogs, fish, and insects appear to follow this pattern. When data on body size at a range of ages are available for such taxa, they are often described well by exponential curves or by power curves that are concave upward. When such data are transformed to mean sizes for ages or age classes, they are likely to fit asymptotic growth models such as the logistic and Gompertz curves. These curves are good descriptions of the behavior of the population mean but poor descriptions of the pattern followed by any individual in the population. Analyzing and presenting data on size at age using mean sizes can thus lead to incorrect interpretations of growth patterns and should be avoided.