Meeting Abstract
111.4 Sunday, Jan. 6 Assessing effects of starvation-induced morphological variations on swimming of larval sand dollars with a novel biomechanical model and video motion analysis CHAN, KYK*; GRUNBAUM, D; Univ. of Washington; Univ. of Washington kychan@uw.edu
Morphologies of planktonic larvae of many marine invertebrates are complex and highly variable. Larval morphologies impose biomechanical constraints on vital ecological functions, including swimming. Earlier modeling studies suggest slight changes in larval morphology could compromise swimming performance. However, environmental variables such as food availability and ambient pH often induce morphological changes in larvae. These natural variations suggest the general hypothesis that environmentally-induced morphological changes are coordinated such that larval abilities to perform ecological functions are conserved. To test this hypothesis, we developed a novel protocol to extract geometric meshes representing detailed 3-dimensional larval morphologies from confocal micrographs and used this model to assess the impacts of morphological variations on larval swimming. Larval sand dollars (Dendraster excentricus) are known to be phenotypically plastic and develop longer ciliated extensions “arms” under food-limited conditions to enhance feeding. In this case study, using non-invasive video motion analysis and the biomechanical model, we tested the specific hypothesis that the starvation-induced morphological changes alter larval swimming. Video analysis results showed that 4-arm larval sand dollars swam in wider helices and had higher oscillatory speeds when starved. In still water, the model larvae had different passive sinking behaviors, suggesting the observed morphological variations had biomechanical implications. The observed differences in larval swimming could be a result of both changes in biomechanics and behaviors. Our results support the general hypothesis that environmentally-induced morphological variations, including starvation, are coordinated to balance ecological functions tradeoffs.
