Meeting Abstract

P2.126  Saturday, Jan. 5  Feeding and Suction Performance in Two Basal Otariid Pinnipeds MARSHALL, C.D.*; ROSEN, D.A.S.; TRITES, A.W.; MARSH, A.; Texas A and M University; University of British Columbia; University of British Columbia; Texas A and M University marshalc@tamug.edu

Feeding performance studies can address questions relevant to foraging ecology and evolution among vertebrates. Trials were conducted to characterize the feeding kinematics and suction performance of Steller sea lions (SSL) and northern fur seals (NFS). We collected behavioral, kinematic and physiological data to test the hypothesis that both species use suction as their primary feeding mode. Food items were presented to the subjects using a platform designed to capture simultaneous frontal and lateral views of feeding events via an underwater video system. Footage was analyzed field-by-field, and suction was measured using a pressure transducer connected to a portable electrophysiological recording system. SSL used suction as their primary feeding method, but also used a bite behavior. In contrast, NFS used a snapping bite in combination with a head strike as their primary feeding mode. Pressure recordings did not detect any measureable subambient pressure forces during NFS feeding events. NFS exhibited a greater gape, a greater gape angle, and a shorter depression of the hyolingual apparatus compared to SSL. The evolution of these divergent prey capture tactics likely constrains the type and size of prey that can be captured, as well as foraging success. The use of head strikes and biting by NFS is likely an adaptation for capturing more elusive prey found in open-ocean mesopelagic habitats. The greater feeding repertoire of SSL likely enables them to feed on a greater variety of prey and prey sizes, in more diverse habitats. Suction feeding behavior by SSL likely increases the capture success of more cryptic, benthic and dermersal fishes.