Meeting Abstract
P3.67 Thursday, Jan. 6 Morphological adaptations for high dexterity and extreme bite fore in the pharyngeal jaw of Black Carp LOPRESTI, E F*; GIDMARK, N J; BRAINERD, E L; Brown University; Brown University; Brown University lopresti.eric@gmail.com
Producing high bite force is essential for durophagous feeding. Eating hard-shelled prey such as snails is limited by two aspects of jaw performance: muscle force production and the ability of the predator to deliver that force appropriately to the prey item. Most durophagous fishes possess flat, highly fused jaws. The Black Carp (Mylopharyngodon piceus) deviates from this pattern, with large molars set into strong pharyngeal elements (derived from ceratobranchial V), where the left and right elements are only weakly fused. In this study, we examined maximum force generation at a variety of gape sizes as well as behavioral patterns of Black Carp in processing and crushing prey. We built artificial prey items using ceramic tubes and coated each size of tube with different numbers of coats of polyurethane, allowing us to test maximum force output of the jaw at multiple gapes. One 0.5 m fish crushed 13.55 and 14.4 mm diameter ceramic tubes with ~500 Newtons of force, while an only slightly bigger food item (16.23 mm) could only elicit a maximum of ~375 Newtons. This decrease in performance (i.e. lower maximum force output) at large gapes was shown by all three individuals and is likely due to limits set by the length-tension properties of muscle. To determine bite patterns, we examined snail shells and ceramic cylinders after they were bitten by Black Carp. We found that the fish attacked real snails in a predictable pattern: they broke the outer whorl at the aperture in every successful attempt. This suggests manipulation into a favorable position within the jaws. This dexterity is permitted by the flexible ligamentous connection between the anterior rami (left and right) of the pharyngeal jaws, as well as a large muscular (and well-innervated) palatal organ.
