![]() Cookiecutter sharks have a unique jaw morphology consisting of a robust semicircular scoop-shaped lower jaw (Meckel’s cartilage) with a fused symphysis. Among elasmobranchs, the ectoparasitic cookiecutter sharks ( Isistius spp.) and their relatives in family Dalatiidae (dalatiids) remain a persistent enigma owing to their distinct feeding morphology and behaviors (Shirai and Nakaya 1992), and more generally to the experimental intractability of deep-sea elasmobranchs. The feeding mechanisms of elasmobranch fishes (sharks, skates, rays) exhibit considerable morphological and behavioral diversity, despite having relatively low taxonomic diversity (Huber and Motta 2004). In addition, the mechanics of producing experimental bites provide new insights related to the necessity for cookiecutter sharks to rotate their body to create nearly symmetrical oval bite wounds. The simulated bite experiment also was useful for assessing factors that potentially affect cookiecutter shark total length estimates when based on natural bite geometrics. Bite simulations were conducted at standardized jaw bite-gape angles and ballistic gelatin was used to approximate prey flesh, from which aspect ratio analysis of bite wound geometrics was used to determine bite wound morphometrics for each species. Copeia 678–682), using three-dimensional printed models of jaws with teeth. To elucidate cookiecutter shark bite dynamics, bites were experimentally simulated for the two cookiecutter shark species the Cookiecutter Shark, Isistius brasiliensis (Quoy JRC, Gaimard, P (1824) Zoologie (3) Imprimerie royale) and the Largetooth Cookiecutter Shark, Isistius plutodus (Garrick JAF, Springer S (1964) Isistius plutodus, a new squaloid shark from the Gulf of Mexico. There is considerable speculation regarding cookiecutter shark bite dynamics given that natural feeding behavior has not been observed. ![]() The jaws and teeth are well suited for feeding by excising a nearly symmetrical oval-flesh bite plug from a variety of prey species including marine mammals, fishes, and squids. Ectoparasitic cookiecutter sharks (Chondrichthyes: Squaliformes: Dalatiidae Isistius) share common features for jaw and teeth structure, in particular, robust lower jaws and dignathic heterodonty (upper teeth crowns are more slender and shorter than the broader and longer lower teeth crowns). ![]()
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