Development of a foraging model for a field population of the South American sun-star Heliaster helianthus

Heliaster helianthus was studied in an intertidal rocky shore habitat in central Peru. The mussel Semimytilus algosus was a predominant prey with an average proportion of 85.5% and 85.7% by number and biomass, respectively. Larger individuals of H. helianthus fed on clumps of S. algosus containing larger mussels, but the biomass distribution of all S. algosus consumed closely resembled that of the natural prey population, except in the smallest predator size-group (≤10.9cm) where small mussels were more strongly represented in the diet. The study suggests that "energy maximization', the core assumption of classic optimal diet choice models, is not relevant to the choice of prey size and meal size in H. helianthus. -from Author