MCZ Lunchtime Seminar

Understanding respiration in arthropods through 3D computational fluid dynamics and surface area

Sarah Losso
Postdoctoral Researcher
Ortega-Hernández Lab

Aerobic respiration is one of the most fundamental functions of metazoans, required to exchange oxygen and produce metabolic energy. The respiratory function of arthropods is typically performed by gills which serve as the location of diffusion of oxygen into the body to be distributed to cells. Due to their varied lifestyles and diverse requirements, arthropods have evolved a broad variety of gill morphologies and sizes that follow the enormous ecological versatility of these organisms. Evidence from sites with exceptional fossil preservation indicate that early arthropods exopodites show different morphology from modern groups and display substantial variability, raising questions about how these different structures would function for respiration. Here we use a combination of approaches including three-dimensional modeling and computational fluid dynamics (CFD) paired with quantification of surface area. Contrary to recent work, three-dimensional CFD analyses demonstrate that water flow velocity does not decrease enough between lamellae to significantly increase oxygen diffusion. Rather, the amount of oxygen that diffuses into the exopodite is controlled by the lamellar surface area. Lamellar surface area is strongly correlated with body size in marine arthropods and trilobites display follow the same trend, supporting the interpretation of exopodites as respiratory structures despite substantial variation in morphology. This approach can provide insights into habitat, lifestyle and activity levels which also impact lamellar surface area.