DePaul University Via Sapientiae College of Liberal Arts & Social Sciences Theses and Dissertations College of Liberal Arts and Social Sciences 3-2010 Morphology and evolution of caudal fin in lamniform sharks Sun H. Kim DePaul University Follow this and additional works at: https://via.library.depaul.edu/etd Recommended Citation Kim, Sun H., "Morphology and evolution of caudal fin in lamniform sharks" (2010). College of Liberal Arts & Social Sciences Theses and Dissertations. 9. https://via.library.depaul.edu/etd/9 This Thesis is brought to you for free and open access by the College of Liberal Arts and Social Sciences at Via Sapientiae. It has been accepted for inclusion in College of Liberal Arts & Social Sciences Theses and Dissertations by an authorized administrator of Via Sapientiae. For more information, please contact [email protected]. Morphology and Evolution of Caudal Fin in Lamniform Sharks A Thesis Presented in Partial Fulfillment of the Requirements for the Degree of Master of Science December 2009 By Sun H. Kim Thesis Advisor: Kenshu Shimada, Ph.D. Department of Biological Sciences College of Liberal Arts and Sciences DePaul University Chicago, Illinois i Table of Contents Approval Page ……………………………………………………………………………………………………….…………….……i Table of Contents……...………………………………………………………………………………………………….…….…….ii List of Figures……………………………………………………………………………………………………………….……..……iii List of Tables…………………………………………………………………………………………………………….……….……..iv Acknowledgements………………………………………………………………………………………………………….….……v Abstract……………………..…………………………………………………………………………………………………….…..….vi Introduction……………………………………………………………………………………………………………………….…..…1 Materials and Methods……………………………………………………………………………………………………….….…4 Examined Specimens………………………………………………………………………………………….…...…….4 Anatomical Examination………………………………………………………………………………..………..…….5 Caudal Fin Terminology………………………………………………………………………………….………..…….6 Measurements……………………………………………………………………………………………….……………...6 Character Mapping………………………………………………………………………………………….…………..…8 Results…………………………………………………………………………………………………………………………………....10 Scyliorhinus retifer………………………………………………………………………………………………….…...10 Mitsukurina owstoni…………………………………………………………………………………..……………..…10 Carcharias taurus………………………………………………………………………………………..………….……11 Odontaspis ferox……………………………………………………………………………….…………..……….……11 Odontaspis noronhai………………………………………………………………………….……………..….…..…11 Pseudocarcharias kamoharai……………………………………………………….……………………...………12 Megachasma pelagios………………………………………………………………………………….….…..………12 Alopias pelagicus……………………………………………………………………………….……….……..…………12 Alopias superciliosus……………………………………………………………….………………….………..………13 Alopias vulpinus………………………………………………………………………………………….…………..……13 Cetorhinus maximus……………………………………..……………………………..…………….……………..…14 Carcharodon carcharias……………………………………………………….…………………….………………..14 Isurus oxyrinchus………………………………………………………………………………………..………………..14 Isurus paucus………………………………………………………………………………………….…….……………..15 Lamna ditropis……………………………………………………………………………….…………….………….…..15 Lamna nasus…………………………………………………………………………………..…………….……………..15 Discussion…………………………………………………………………………………………..…………………….……………..17 Phylogenetic Mapping of Caudal Fin Data……………………………………………………….….………..17 Three Caudal Fin Types in Lamniforms and Their Evolutionary History…………….…………..19 Functional Differences Based on Caudal Fin Types………………………………………………….…...21 References……………………………………………………………………………………………………….……….………….….25 Appendix 1……………………………………………………………………………………………………….……….…………….40 Appendix 2……………………………………………………………………………………………………….……….…………….41 ii List of Figures Figure 1 All 15 lamniform species……………………………………………………………………….………….30 Figure 2 Medical imaging technology used to radiographically………………………………………31 examine shark specimens Figure 3 Schematic drawings of lamniform caudal fin showing………………………………………32 nomenclature and measured variables Figure 4 Examples of radiographs showing caudal fin anatomy………………………………………33 in one carcharhiniform and 15 lamniform species Figure 5 Mapping of average values of Cobb’s angle and hypochordal…………………………..35 angle onto morphology-based phylogenetic tree of lamniforms along with schematic illustrations of caudal fin showing its outline and skeletal arrangement Figure 6 Mapping of average values of Cobb’s and hypochordal…………………………………….36 angle onto molecular-based phylogenetic tree of lamniforms along with schematic illustrations of caudal fin showing its outline and skeletal arrangement Figure 7 Three types of caudal fin in lamniforms and their possible……………………………….32 evolutionary scenarios iii List of Tables Table 1 List of examined specimens in this study………………………………………………………….38 Table 2 Average value of heterocercal angle, hypocercal angle,…………………………………..39 Cobb’s angle, and hypochordal angle data for each species iv Acknowledgements I thank the following individuals who were involved in the acquisition, loan, or transportation of examined specimens: A. Y. Suzumoto (BPBM); M. A. Rogers, K. Swagel, M. W. Westneat, P. Willink (FMNH); K. Nakaya (HUMZ); J. A. Seigel (LACM); K. E. Hartel, A. Williston (MCZ); C. Klepadlo, P. A. Hastings, H. J. Walker (SIO); L. M. Page, R. H. Robins (UF); D. W. Nelson (UMMZ); J. Finan, L. Palmer, S. Raredon, S. Smith; E. Wilbur, D. Pitassy, and J. T. Williams (USNM); M. Miya (Natural History Museum and Institute, Chiba, Japan), S. J. Arceneaux, R. L. Humphreys, Jr. (Pacific Islands Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration); S. R. Van Sommeran (Pelagic Shark Research Foundation, Capitola, California); B. L. Beatty (New York College of Osteopathic Medicine); and J. L. Castillo-Geniz (Instituto Nacional de la Pesca, Baja California, México). Special thanks go to K. Gray, B. Karl, J. Hickey, P. Myefski, A. Nicholas, C. Rigsby, L. Wansk (Children's Memorial Hospital, Chicago, Illinois) for assisting me with CT scanning and x-ray shooting of examined specimens. Financial support was made by the Environmental Science Program, Department of Biological Sciences, and University Research Council at DePaul University, Chicago, Illinois, that were provided to, or awarded to, K. Shimada. I would also like to thank M. Silliker for her continued support since I came to DePaul. I also thank A. Ippolito and W. Aguirre for sitting on my thesis committee. Special thanks to K. Shimada for his patience and guidance as my mentor and supervising professor of this project. Finally, I would like to thank my friends and family for supporting me throughout all these years. v Abstract Sharks have a distinct asymmetrical caudal fin referred to as heterocercal tail that is a key characteristic of the group and has diversified within sharks in ways that are correlated with lifestyle. However, practically no study examining the evolutionary trend and history of the caudal fin morphology within a specific shark group exists. Here, I examined the caudal fin morphology and evolution of the shark order Lamniformes that consists of 15 extant species with diverse behaviors and lifestyles. The goals of this study are to describe the skeletal morphology of the caudal fin in each lamniform species based primarily on radiographic analysis, to examine the evolutionary pattern and history of the caudal fin through phylogenetic mapping, and to relate different caudal fin types observed in lamniforms to their known behaviors and life styles. This study suggests that caudal fins with a more horizontally directed curvature of the vertebral column are plesiomorphic, whereas those with a large dorsally directed curvature of the vertebral column are apomorphic within Lamniformes. It also shows that caudal fins with posteriorly directed hypochordal rays are plesiomorphic, and that those with ventrally directed hypochordal rays are apomorphic within Lamniformes. Three basic caudal fin types are recognized in extant lamniforms on the basis of these skeletal variables. One important discovery form the recognition of the three fin types is that the evolution of external morphology of caudal fin does not necessarily correspond to the evolution of its internal (skeletal) anatomy in lamniform sharks. Certain behaviors and lifestyles seen in different lamniforms are correlative with the different caudal fin types. A less asymmetrical tail is a derived feature in lamniforms that evolved for fast swimming to capture fast swimming prey. vi Introduction The structure and biomechanics of the caudal fin of fishes have been studied by many researchers (e.g., Agassiz, 1833; Ryder, 1884; Garman, 1913; Thomson, 1976; Thomson & Simanek, 1977; Lauder, 2000). In particular, the caudal fin of sharks (Chondrichthyes: Elasmobranchii) have received considerable attention due to the asymmetrical form referred to as heterocercal tail, or heterocercy (e.g. Thomson, 1976; Thomson & Simanek, 1977; Lauder, 1989, 2000; Liao & Lauder, 2000a, 2000b; Lauder et al., 2003; Lingham-Soliar, 2005a, 2005b). Heterocercy in sharks occurs because the enlarged, dorsoposteriorly directed dorsal (upper) lobe of the caudal fin relative to the ventroposteriorly directed ventral (lower) lobe as the notochord, or vertebral column, extends into the dorsal lobe and forms its axis (Goodrich, 1958). It is related to swimming that produces forces acting on the center of balance to give sharks fine control for climbing, diving, and turning (Thomson, 1976, 1990). Understanding the sequence of anatomical modification over the course of evolution is a central theme in comparative morphology. For example,