Mouthpart morphology of three calanoid copepods from Australian temporary pools: Evidence for carnivory

Abstract

The mandibles, first and second maxillae, and maxillipeds of Boeckella major, B. pseudo-chelae, and Hemiboeckella searli from temporary pools of the upper River Murray catchment were dissected off and examined by light microscopy for features associated with carnivorous feeding. In B. major adaptations for carnivory are enlarged ventral mandibular teeth, strong falciform medial setae on the second maxillae, falciform endopodal setae on the maxilliped, large body size and large mouthpart size in relation to body size. Its mandibular edge index is 772, in the upper omnivore range. B. major is predicted to be an omnivore with strong carnivorous tendencies and able to handle large prey items. Carnivorous features in H. searli are enlarged ventral mandibular teeth, a mandibular edge index of 1395, and strong unguiform and falciform setae on the second maxillae. It is predicted to be an omnivore with moderate carnivorous tendencies, but unable to handle prey as large as can B. major. In B. pseudochelae the only adaptations for carnivory are an edge index of 1080 and falciform setae on the maxilliped. It is predicted to be an omnivore with herbivorous tendencies. Examination of gut contents confirmed these predictions. B. major guts contained 19 animal taxa, mainly planktonic cladocerans, copepods and rotifers, H. searli 12 taxa, mainly copepods and rotifers, and B. pseudochelae 8 taxa, mainly rotifers. All had consumed algae. We suggest that predation by B. major may be an important factor affecting community structure in fishless Australian temporary pools. © 1999, Copyright Taylor & Francis Group, LLC.