Meeting Abstract
To manipulate their external environment, animals must use the degrees of freedom (DoFs) afforded by their musculoskeletal system to control the DoFs of external objects. For example, grasping a food item with the hand and moving it to the mouth typically requires six DoFs to control the translation and rotation of the food. Suction feeding fishes encounter a similar problem but rather than grasp food items directly, they use a complex linkage of over 10 skeletal elements to manipulate the fluid surrounding the food to capture and transport it to the pharyngeal jaws or esophagus. Do a similar number of degrees of freedom underlie both motor tasks? Previous studies using two-dimensional four-bar linkages suggest fish use just one to three DoFs. However, the skull has over 10 potential DoFs of motion. To answer this question, we created a 13-bar cranial linkage model of the channel catfish first and second jaw arches and validated the model using in vivo data collected using XROMM (X-ray reconstruction of moving morphology). We find that the skull allows at least 14 DoFs of substantial motions (those that affect fluid flow). However, we only observed motion along five of these DoFs. These results show that the manipulation of fluid during suction feeding, though in some ways more complex than grasping a single food item, uses a similar number of DoFs of motion, suggesting analogous strategies in controlling the motion of external objects across terrestrial and fluid domains. Funding: NSF 1612230, 1655756.
