Meeting Abstract
30.1 Wednesday, Jan. 5 Energetics of burrowing by the cirratulid polychaete, Cirriformia moorei DORGAN, Kelly M.*; LEFEBVRE, Stephane C.; STILLMAN, Jonathon H.; KOEHL, M. A. R.; University of California, Berkeley; Romberg Tiburon Center for Environmental Studies, San Francisco State University; Romberg Tiburon Center for Environmental Studies, San Francisco State University; University of California, Berkeley kelly.dorgan@berkeley.edu
Burrowing has been considered much more energetically expensive than other forms of locomotion, but previous studies were based solely on external work calculations and lacked an understanding of the mechanical responses of sediments to forces applied by burrowers. Muddy sediments are elastic solids through which burrows are extended by fracture; relatively small forces applied to the burrow wall are amplified at the tip of the crack, which extends when enough stress is applied to overcome the fracture toughness of the sediment. Here we present data on the energetics of burrowing by the polychaete, Cirriformia moorei, including oxygen consumption rates and concentrations of the anaerobic metabolite tauropine and the energy-storage molecule phosphocreatine. None of these components were significantly different between burrowing and resting worms. External work was calculated as the sum of the work to extend the burrow by fracture and elastic work done to displace sediment as the worm moves into the newly formed burrow. Comparison of aerobic and anaerobic energy components with calculations of external work suggests that the energy required to burrow could come from aerobic or anaerobic sources. Also, increases in oxygen consumption rates or anaerobic metabolites were predicted to be very small and not detectable considering the variability observed across individuals. Although the energy per distance traveled predicted from external work is high, the resulting increase in metabolism during locomotion was undetectable, likely because of the slow speeds and short distances traveled by burrowers.
