The Early Ontogeny of Feeding in Two Shark Species: Developmental Aspects of Morphology, Behavior, and Performance by David C. Lowry A dissertation submitted in partial fulfillment Of the requirements for the degree of Doctor of Philosophy Department of Biology College of Arts and Sciences University of South Florida Major Professor: Philip Motta, Ph.D. Robert Hueter, Ph.D. Susan Bell, Ph.D. Florence Thomas, Ph.D. Date of Approval: September 19, 2005 Keywords: ecomorphology, aquatic feeding, modulation, variability, developmental trajectory © Copyright 2005, David C. Lowry Dedication This work is dedicated to researchers everywhere that seek knowledge for its inherent value and strive for its practical application every day. Acknowledgements I am deeply appreciative of the support provided by my family and friends over the course of this study and throughout my life. Volunteer laboratory assistance during various portions of this work was graciously provided by Andrey Castro, Coral Gehrke, Carey Heinrich, Daniel Huber, Sarah Koh, Sonia Lowry, Kyle Mara, Michael Matott, Ramani Rasile, and Alpa Wintzer. Animal husbandry advice and practices were supplied by Kristen Mathews, Jack Morris, Chris Schreiber, and Michael Schulte. Specimens were obtained through Mote Marine Laboratory, Sarasota, FL and SeaWorld Adventure Park, Orlando, FL. Philip Motta, Robert Hueter, Susan Bell, and Florence Thomas contributed to the content and presentation of the manuscript. This research was funded in part by Mote Marine Laboratory, a Tharpe Endowed Scholars Grant through the University of South Florida, and the PADI Project A.W.A.R.E. Foundation Grant Program. All animal maintenance and experimental handling procedures were approved by the University of South Florida Institutional Animal Care and Use Committee under protocol numbers 1709 and 2299. Table of Contents List of Tables ..................................................................................................................... iii List of Figures......................................................................................................................v Abstract............................................................................................................................. vii Chapter 1: Introduction.......................................................................................................1 Aquatic Feeding.......................................................................................................2 The Ontogeny of Feeding ........................................................................................4 Goals ........................................................................................................................6 Significance..............................................................................................................7 Chapter 2: The ontogeny of feeding behavior and cranial morphology in the leopard shark Triakis semifasciata (Girard 1854): a longitudinal perspective .............9 Abstract....................................................................................................................9 Introduction............................................................................................................11 Methods and Materials...........................................................................................15 Experimental Animals................................................................................15 Filming Techniques....................................................................................15 Morphological Measurements ...................................................................19 Statistical Analyses ....................................................................................20 Results ....................................................................................................................23 Scaling of Kinematics ................................................................................25 Kinematic Trends.......................................................................................26 Scaling of Morphology...............................................................................35 Discussion..............................................................................................................38 Chapter 3: The ontogeny of feeding behavior and cranial morphology in the whitespotted bambooshark Chiloscyllium plagiosum (Bennett 1830): a longitudinal perspective...............................................................................................45 Abstract..................................................................................................................45 Introduction............................................................................................................47 Methods and Materials...........................................................................................50 Experimental Animals................................................................................50 Filming Techniques....................................................................................50 Morphological Measurements ...................................................................53 Statistical Analyses ....................................................................................54 Results ....................................................................................................................57 Scaling of Kinematics ................................................................................58 Kinematic Trends.......................................................................................58 i Scaling of Morphology...............................................................................61 Discussion..............................................................................................................68 Chapter 4: The comparative ontogeny of feeding performance in two sharks: the leopard shark Triakis semifasciata and the whitespotted bambooshark Chiloscyllium plagiosum..............................................................................................72 Abstract..................................................................................................................72 Introduction............................................................................................................74 Methods and Materials...........................................................................................77 Experimental Animals................................................................................77 Experimental Techniques...........................................................................78 Statistical Analyses ....................................................................................83 Results ....................................................................................................................87 Scaling of Performance..............................................................................89 Behavioral Effects on Performance...........................................................91 Discussion..............................................................................................................96 Ecological and Evolutionary Implications ..............................................101 References........................................................................................................................104 About the Author ................................................................................................... End Page ii List of Tables Table 1: Regression parameters for kinematic variables versus total length (cm) for Triakis semifasciata. ........................................................................................25 Table 2: Principal component loadings of kinematic variables associated with capture sequences in Triakis semifasciata. ......................................................27 Table 3: Results of RM ANOVAs performed separately on each principal component from a PCA of prey capture kinematics in Triakis semifasciata (N=4)................................................................................................................28 Table 4: Parameters for log-log regressions against total length (cm) of external morphological variable data measured on live specimens of Triakis semifasciata......................................................................................................36 Table 5: Parameters for log-log regressions against total length (cm) of morphological variable data taken from dead specimens only of Triakis semifasciata......................................................................................................37 Table 6: Regression parameters for kinematic variables versus total length (cm) for Chiloscyllium plagiosum..................................................................................59 Table 7: Principal component loadings of kinematic variables associated with capture sequences in Chiloscyllium plagiosum................................................60 Table 8: Results of RM ANOVAs performed separately on each principal component from a PCA of prey capture kinematics in Chiloscyllium plagiosum (N=5). .............................................................................................63 Table 9: Parameters for log-log regressions against total