Functional anatomy of Bering Wolffish, Anarhichas orientalis, jaws

Abstract Oral jaw morphology plays a large role in determining an organism’s ecological niche. The Bering wolffish, Anarhichas orientalis , feeds almost exclusively on hard-shelled prey, a niche typically defined by increased bite forces, robust bones and teeth, and greater mechanical advantage in the jaw lever system. The anatomical features associated with the feeding apparatus were examined to better understand the link between morphology and feeding behavior. The Bering wolffish possesses the largest oral jaw muscles, relative to body size, for any fish measured to date. The three lateral branches of the adductor mandibulae are oriented at efficient force-conducting angles that insert upon the lower jaw with increased mechanical advantage. The skull bones are modified to accommodate large jaw muscles and to provide pronounced origins for them. Wolffish teeth are robust and are morphologically diverse to meet different feeding demands. Also, a novel ligamentous connection between the articular and premaxilla was identified. Allometric growth was explored for muscle masses and head dimensions. These specialized morphological features indicate several adaptations to better enable feeding on hard-bodied prey by the Bering wolffish.