title: Swimming speed of larval snail does not correlate with size and ciliary beat frequency.
abstract: Many marine invertebrates have planktonic larvae with cilia used for both propulsion and capturing of food particles. Hence, changes in ciliary activity have implications for larval nutrition and ability to navigate the water column, which in turn affect survival and dispersal. Using high-speed high-resolution microvideography, we examined the relationship between swimming speed, velar arrangements, and ciliary beat frequency of freely swimming veliger larvae of the gastropod Crepidula fornicata over the course of larval development. Average swimming speed was greatest 6 days post hatching, suggesting a reduction in swimming speed towards settlement. At a given age, veliger larvae have highly variable speeds (0.8-4 body lengths s(-1)) that are independent of shell size. Contrary to the hypothesis that an increase in ciliary beat frequency increases work done, and therefore speed, there was no significant correlation between swimming speed and ciliary beat frequency. Instead, there are significant correlations between swimming speed and visible area of the velar lobe, and distance between centroids of velum and larval shell. These observations suggest an alternative hypothesis that, instead of modifying ciliary beat frequency, larval C. fornicata modify swimming through adjustment of velum extension or orientation. The ability to adjust velum position could influence particle capture efficiency and fluid disturbance and help promote survival in the plankton.
authors.affiliation: Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America.
authors.forename: Kit Yu Karen
authors.initials: KY
authors.lastname: Chan
authors.affiliation: Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America.
authors.forename: Houshuo
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York, United States of America.
authors.forename: Dianna K
authors.initials: DK
authors.lastname: Padilla
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D002923:Cilia / Q000502:physiology*; D007814:Larva / Q000502:physiology*; D012908:Snails / Q000502:physiology*; D013550:Swimming / Q000502:physiology*