DOES IT PUMP? AN INVESTIGATION INTO THE RELATIONSHIP BETWEEN MORPHOLOGICAL VARIETY AND FEEDING STRATEGIES IN ARCHAEOCYATHA

The earliest uncontested animal reef builders, the archaeocyathans, emerged and quickly dominated Early Cambrian (530Ma) reef ecosystems before rapidly declining by the Middle Cambrian. The question of how archaeocyathans effectively gathered nutrients (fed) has been debated and has, in part, supported their interpretation as calcifying sponges. Previous studies have suggested that these organisms could have fed entirely through passive (or unaided) filter feeding. This differs from most modern sponges who actively pump water via flagellated collar-cells (choanocytes) through their skeletons to feed. We use 3-dimensional models, based on a variety of species and morphotypes, and computational fluid dynamics (CFD) to analyze the fluid flow through a wide range of archaeocyathan body plans. These data are used to examine the functional significance of a wide variety of structural differences between species of Archaeocyatha. Our preliminary results suggest that a solely passive filter feeding lifestyle may have been unlikely, and that morphological differences within archaeocyathans may have represented morphological adaptations to different flow conditions.