Meeting Abstract

39.5  Jan. 6  The Scaling of Suction Feeding STAAB, KL*; SUMMERS, AP; STROTHER, JA; VAN WASSENBERGH, S; George Washington University; UC Irvine; UC Irvine; University of Antwerp, Belgium kstaab@gwu.edu

We measured suction performance in a size series of great sculpin, Myoxocephalus polyacanthocephalus, to test hypotheses predicting the scaling of negative pressure. Two theoretical models of suction generation in fishes predict measured pressures with acceptable accuracy; however they differ in their prediction of the scaling of negative pressure in an isometrically growing fish. Maximal suction performance of 12 sculpins ranging from 164mm to 337mm standard length and 85 to 710 grams was used both as a metric of performance and to estimate timing variables needed as input for the theoretical models. We also measured buccal volume using silicone casts of both the relaxed and expanded buccal cavities in each fish. We compared the casting data to data inferred by modeling the buccal cavity as a series of truncated cones with diameters measured from the cast. Estimated volumes were consistently lower than actual volumes and just five joined truncated cones gave a volume within 10% of the volume estimated from 100 truncated cones. The pressure generated during feeding does not change significantly as this sculpin grows, however the buccal volume grows allometrically. We estimated the power generated during feeding events both by taking the product of pressure and volume over the feeding event and by multiplying the surface area of the buccal chamber, the change in pressure, and a calculated velocity of the feeding events. We found that power scales approximately with the square of length. Our data on suction pressure support the hypothesis that pressure is size invariant, which raises the prospect that for relatively isometric species, measurements from an individual can summarize performance of the ontogenetic series.