MOORE, S.W.: Scrambled Eggs: Biomechanical Aspects of Developmental Ecology

Gametes, embryos, and larvae are not exempt from the laws of physics. However, the physical forces that dominate their tiny world (viscosity, surface tension, etc.) are different than the ones that dominate our relatively large world (e.g., weight, inertia). Because of this, we often overlook, or at least underestimate, the critical role that physics plays in determining the success of these early life history stages, and in driving the evolution of developmental pathways and life-history strategies. In this presentation, I provide a brief overview of some basic biomechanical scaling laws as they relate specifically to small, squishy, early life history stages interacting with a physical environment. Then I explore what some biomechanical models and related experiments have taught us about developmental ecology. Consider coral spawning, for example. Many coral species release their gametes in bundles containing a dozen or more buoyant eggs. Hydrodynamic models show that this simple expedient of clumping eggs together allows them to better outrun turbulent mixing and may more than double the concentration of gametes at the sea surface, where fertilization takes place. The model also shows why this strategy will not work for most other spawning organisms. Biomechanics has other important implications for gamete dispersal, larval feeding, recruitment patterns, and morphogenetic processes. Developmental biologists/ecologists would thus do well to supplement their already powerful descriptive, molecular, and genetic approaches to understanding development with biomechanical and other physics-centered approaches.