title: Morphology does not predict performance: jaw curvature and prey crushing in durophagous stingrays.
abstract: All stingrays in the family Myliobatidae are durophagous, consuming bivalves and gastropods, as well as decapod crustaceans. Durophagous rays have rigid jaws, flat teeth that interlock to form pavement-like tooth plates, and large muscles that generate bite forces capable of fracturing stiff biological composites (e.g. mollusk shell). The relative proportion of different prey types in the diet of durophagous rays varies between genera, with some stingray species specializing on particular mollusk taxa, while others are generalists. The tooth plate module provides a curved occlusal surface on which prey is crushed, and this curvature differs significantly among myliobatids. We measured the effect of jaw curvature on prey-crushing success in durophagous stingrays. We milled aluminum replica jaws rendered from computed tomography scans, and crushed live mollusks, three-dimensionally printed gastropod shells, and ceramic tubes with these fabricated jaws. Our analysis of prey items indicate that gastropods were consistently more difficult to crush than bivalves (i.e. were stiffer), but that mussels require the greatest work-to-fracture. We found that replica shells can provide an important proxy for investigations of failure mechanics. We also found little difference in crushing performance between jaw shapes, suggesting that disparate jaws are equally suited for processing different types of shelled prey. Thus, durophagous stingrays exhibit a many-to-one mapping of jaw morphology to mollusk crushing performance.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Toronto at Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4 matthew.kolmann@mail.utoronto.ca.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Kolmann
authors.affiliation: Department of Biological Sciences, New Jersey Institute of Technology, University Heights, Newark, NJ 07102, USA.
authors.forename: Stephanie B
authors.initials: SB
authors.lastname: Crofts
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Am Muehlenberg 1, 14424 Potsdam, Germany.
authors.forename: Mason N
authors.initials: MN
authors.lastname: Dean
authors.affiliation: Friday Harbor Laboratories, University of Washington, 620 University Dr., Friday Harbor, WA 98250, USA.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Summers
authors.affiliation: Department of Biological Science, University of Toronto at Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4.
authors.forename: Nathan R
authors.initials: NR
authors.lastname: Lovejoy
mesh_terms: D060105:Animal Shells; D000818:Animals; D001696:Biomechanical Phenomena; D001732:Bite Force; D049872:Bivalvia; D004032:Diet; D005247:Feeding Behavior; D049851:Gastropoda; D007568:Jaw / Q000033:anatomy & histology* / Q000502:physiology*; D008954:Models, Biological; D012860:Skates, Fish / Q000033:anatomy & histology* / Q000502:physiology*
keywords: Biomaterials; Bite force; Myliobatidae; Rapid prototyping; Toughness