November 30 2011

12:00 LSB 2320

Kelly Dorgan
Marine Biology Research Division, UC San Diego

Mechanics and Energetics of Burrowing in Marine Sediments


Marine muds are elastic solids through which animals move by propagating a crack-shaped burrow. Modeling worms as wedges provides insight on how burrowing behaviors depend on the mechanical properties (stiffness and fracture toughness) of sediments as well as sizes and morphologies of burrowers. This mechanism of burrowing by fracture is consistent with descriptions of burrowing across phyla and helps
explain long-puzzling anatomies and behaviors of burrowing animals. It also raises questions about the reputed high energetic cost of burrowing. We measured aerobic and anaerobic components of metabolism and calculated external work to burrow and found that the cost-per-distance was high, but the cost-per-time, or resulting increase in metabolism, was very small, undetectable in our experiments. Considerable phylogenetic and morphological diversity exists among burrowers, and understanding how individual organisms interact with their environment is important in linking morphological and functional diversity.















































































































































































































































































































































































































































































































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