THE ALLOMETRY OF FEEDING, ENERGETICS, AND BODY SIZE IN THREE SEA ANEMONE SPECIES

Abstract

Three sea anemone species (Anthopleura elegantissima, A. xanthogrammica, and Metridium senile) were used to examine allometric and energetic properties of body size in passive suspension feeders. Photographs of expanded anemones in the field showed that projected feeding surface area (tentacle crown) as a function of body size increased at, or less than, the rate expected for a geometric solid (0.45-0.73 power or weight). Energetic cost, measured as weight loss, was found to relate differently to body size for each of the three species (0.77-1.08 power of weight). Number of prey captured was closely related to the feeding surface area in all three species(0.36-0.7 power of weight). The exponent for prey biomass capture as a function of body weight was greater than that for energetic cost in A.xanthogrammica, (1.65 power of weight), but not for the other two species (0.33-0.54 power of weight). Prey size increased with predator size only in A. xanthogrammica (up to 10-cm anemone diameter), accounting for the higher increase in biomass capture. Numbers of prey captured by A. xanthognammica continued to follow a surface-area function. Once the largest size classes of prey can be captured, further energy intake is probably directly related to feeding surface.