The tooth, the whole tooth and nothing but the tooth: tooth shape and ontogenetic shift dynamics in the white sharkCarcharodon carcharias

Abstract

Results from this study of the white shark Carcharodon carcharias include measurements obtained using a novel photographic method that reveal significant differences between the sexes in the relationship between tooth cuspidity and shark total length, and a novel ontogenetic change in male tooth shape. Males exhibit broader upper first teeth and increased distal inclination of upper third teeth with increasing length, while females do not present a consistent morphological change. Substantial individual variation, with implications for pace of life syndrome, was present in males and tooth polymorphism was suggested in females. Sexual differences and individual variation may play major roles in ontogenetic changes in tooth morphology in C. carcharias, with potential implications for their foraging biology. Such individual and sexual differences should be included in studies of ontogenetic shift dynamics in other species and systems.

Non‐trophic impacts from white sharks complicate population recovery for sea otters

“…Future work must address persistent knowledge gaps as they relate to sharks interacting with bitten otters. In particular, bite forensics (French et al, ) and possibly genetic tools (Fotedar, Lukehurst, Jackson, & Snow, ) could generate greater discernment regarding the sex, size, or age classes of sharks that interact with otters. Through greater ecological understanding, knowledge gains can better contextualize the novel emergence and recent acceleration of mistargeting otters by sharks.…”

Do sharks exhibit heterodonty by tooth position and over ontogeny? A comparison using elliptic Fourier analysis

“…Traditionally, tooth function in elasmobranchs has been inferred from morphology (Cappetta, , ; Frazzetta, ), but recent studies that have incorporated measures of performance show that this relationship is complex (Corn, Farina, Brash, & Summers, ; Huber, Claes, Mallefet, & Herrel, ; Whitenack & Motta, ). The attribution of ecology to morphology has been straightforward in some species, such as white sharks ( Carcharodon carcharias ; Ferrara et al, ; French et al, ), sandtiger sharks ( Carcharias taurus ; Ferrara et al, ), horn sharks ( Heterodontus francisci ; Huber, Eason, Hueter, & Motta, ; Summers, Ketcham, & Rowe, ), bonnethead sharks ( Sphyrna tiburo ; Mara, Motta, & Huber, ; Wilga & Motta, ), and cownose rays ( Rhinoptera bonasus ; Kolmann, Huber, Motta, & Grubbs, ). However, the traditional method of attributing form to function has not been helpful for other elasmobranchs.…”

“…As ontogenetic dietary shifts in the diversity, size, and material properties of shark prey are common (Barry, Condrey, Driggers, & Jones, ; Bethea et al, ; Bethea, Buckel, & Carlson, ; Estrada, Rice, Natanson, & Skomal, ; Habegger et al, ; Lowe, Wetherbee, Crow, & Tester, ; Newman, Handy, & Gruber, ), it is likely that a concomitant change in tooth morphology (i.e., ontogenetic heterodonty) may occur to meet the functional demands of these dietary shifts. Ontogenetic changes in diet and dentition have been characterized in heterodontiform (Powter, Gladstone, & Platell, ; Reif, ; Summers et al, ) and lamniform (French et al, ; Powlik, ; Tricas & McCosker, ) sharks, but have not been fully investigated in the dignathic heterodont carcharhiniforms to date (but see Raschi, Musick, & Compagno, ). These studies have primarily evaluated ontogenetic heterodonty using qualitative methods (McCosker, ; Powlik, ; Raschi et al, ; Reif, ; Summers et al, ; Tricas & McCosker, ), but recent studies have begun using quantitative analyses as a more robust approach (French et al, ; Powter et al, ).…”

“…Ontogenetic changes in diet and dentition have been characterized in heterodontiform (Powter, Gladstone, & Platell, ; Reif, ; Summers et al, ) and lamniform (French et al, ; Powlik, ; Tricas & McCosker, ) sharks, but have not been fully investigated in the dignathic heterodont carcharhiniforms to date (but see Raschi, Musick, & Compagno, ). These studies have primarily evaluated ontogenetic heterodonty using qualitative methods (McCosker, ; Powlik, ; Raschi et al, ; Reif, ; Summers et al, ; Tricas & McCosker, ), but recent studies have begun using quantitative analyses as a more robust approach (French et al, ; Powter et al, ).…”

“…In general, studies of shark tooth morphology have often been conducted using linear or geometric morphometrics (French et al, ; Marramà & Kriwet, ; Nyberg, Ciampaglio, & Wray, ; Whitenack & Gottfried, ; Whitenack & Motta, ), but these methods do not fully capture the complexity of tooth morphology in most instances (Crampton, ). Unlike linear and geometric morphometrics, elliptic Fourier analysis (EFA) is able to create a more accurate representation of complex organismal morphologies by characterizing the whole outline of the structure of interest (Ferson, Rohlf, & Koehn, ; Kuhl & Giardina, ).…”