Functional morphology of the feeding apparatus of chain pickerel, Esox niger: Adaptations of manipulation and consumption of large live prey

Fish of the family Esocidae include the chain pickerel, northern pike, and muskellunge. These fish are ambush predators that can capture and consume prey, such as other fish, aquatic birds and mammals that are more than 50% their body size. They capture prey by seizing it between heavily toothed jaws that have a wide gape (mouth opening). Once captured large struggling prey is manipulated so the head is facing into the mouth for swallowing. This is problematic because most fish would have to open their mouths to reposition the prey, giving the prey the opportunity to escape. Yet, these fish have a method of moving their mouth over the prey without letting go. Here we examine and describe the anatomy of the feeding apparatus of Esox niger, the chain pickerel to determine the roles of the cranial elements during large-prey manipulation. The oral and pharyngeal jaws, and all tooth pads with in the buccopharyngeal cavity are examined. Manual manipulation of the feeding anatomy suggests that the prey manipulation mechanism may be similar to the pterygoid walk that snakes perform, as a “hands-free” way of “walking" their jaws along their prey. A new mechanism of prey manipulation in the these fish is proposed, and potential implications for biomimetic tool design are discussed.