Effect of food stress on Obelia geniculata zooid differentiation

Abstract

Colonial hydrozoans are well known for their phenotypic plasticity. Colonies of the Obelia geniculata (Cnidaria:Hydrozoa) maintain distinctly different zooids that are specialized for different tasks. It is not known, however, whether O. geniculata is capable of modulating the relative numbers of these structures in response to environmental conditions. In this study I subject O. geniculata to feeding regimes designed to simulate starvation, food-limited, and abundant-food conditions, and measure the numbers of each zooid type to see if they respond to these treatments.