Meeting Abstract
P1.53 Sunday, Jan. 4 Suction and ram feeding kinematics in two divergent odontocetes KANE, E. A.*; MARSHALL, C. D.; Department of Wildlife and Fisheries Science, Texas A and M University; Department of Marine Biology, Texas A and M University at Galveston ekane@tamu.edu
The feeding behavior and morphology of some species of odontocetes are convergent with other aquatic suction feeders; however, few cetacean kinematic feeding studies have been conducted. To explore suction and ram feeding in odontocetes, controlled feeding trials using 7 beluga whales (Delphinapterus leucas) and 7 Pacific white-sided dolphins (PWD; Lagenorhynchus obliquidens) were conducted. Kinematic analysis used anatomical landmarks to characterize feeding behavior. Mean kinematic variables for belugas were: max gape = 7.18 cm +/- 2.78, time to max gape = 250 ms +/- 170, max gape angle = 16.9 +/- 4.89, max gape angle opening velocity = 118/s +/- 50.0, max gape angle closing velocity = 120/s +/- 48.7, max hyoid depression = 2.80 cm +/- 1.87, time to max hyoid depression = 397 ms +/- 339, max prey velocity = 227 cm/s +/- 98.9, and gape cycle duration = 526 ms +/- 310. Lateral gape occlusion was observed for belugas in all trials; max percent of rostrum length occluded at initial prey movement = 82.0% +/- 8.35; height-to-width ratio of the pursed aperture in belugas was nearly circular. Beluga pursed gape variables were: max pursed gape angle = 76.4 +/- 20.7, max pursed gape angle opening velocity = 872/s +/- 427, max pursed gape angle closing velocity = 1092/s +/- 509. All PWD kinematics were significantly different than belugas except max gape, max gape angle, and hyoid depression. Some pursing in PWD was observed in most trials; max percent length occluded = 40.5% +/- 25.6 and pursed aperture ratio was non-circular. Ram-suction index was -0.03 +/- 0.37 for belugas and +0.32 +/- 0.40 for PWD. Belugas appear highly specialized for the generation of suction despite RSI values. Ram feeding was dominant in PWD, but some suction ability was observed.
