Computer simulation of deposit-feeding by sand dollars and sea biscuits (Echinoidea: Clypeasteroida)

Abstract

A computer simulation of deposit feeding by several species of sand dollars and sea biscuits is presented. The simulation uses the size distribution of food-gathering podia, areal contribution of sediment size classes to total sediment surface area and empirically determined collection coefficients for each podial size collecting each sediment particle size. The simulation generates frequency data for the particles encountered and those successfully harvested. G tests show that the simulation results accurately mimic the distribution of particle sizes found in the food grooves of feeding animals. The simulation can be used to predict what the species would be expected to collect from other real or hypothetical sediment mixtures. This allows a theoretical comparison of feeding behavior between species which do not normally co-occur: for example, Echinarachnius parma (Lamarck), Melitta isometra Harold & Telford and Leodia sexiesperforata (Leske) would all draw over 90% of their diet from the 100–400 ftm particle size classes. The simulation also permits calculation of the numbers of particles contacted but not collected, which indicates the relative effort of feeding on different sediment mixes.