Marshall Christopher D, Rosen David A S, Trites Andrew W
Texas A&M University, Department of Marine Biology, Galveston, TX 77553, USA Texas A&M University, Department of Wildlife and Fisheries Sciences, College Station, TX 77840, USA
Marine Mammal Research Unit, Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
J Exp Biol. 2015 Oct;218(Pt 20):3229-40. doi: 10.1242/jeb.126573. Epub 2015 Oct 8.
Feeding performance studies can address questions relevant to feeding ecology and evolution. Our current understanding of feeding mechanisms for aquatic mammals is poor. Therefore, we characterized the feeding kinematics and performance of five Steller sea lions (Eumetopias jubatus) and six northern fur seals (Callorhinus ursinus). We tested the hypotheses that both species use suction as their primary feeding mode, and that rapid jaw opening was related to suction generation. Steller sea lions used suction as their primary feeding mode, but also used a biting feeding mode. In contrast, northern fur seals only used a biting feeding mode. Kinematic profiles of Steller sea lions were all indicative of suction feeding (i.e. a small gape, small gape angle, large depression of the hyolingual apparatus and lip pursing). However, jaw opening as measured by gape angle opening velocity (GAOV) was relatively slow in Steller sea lions. In contrast to Steller sea lions, the GAOV of northern fur seals was extremely fast, but their kinematic profiles indicated a biting feeding mode (i.e. northern fur seals exhibited a greater gape, a greater gape angle and minimal depression of the hyolingual apparatus compared with Steller sea lions). Steller sea lions produced both subambient and suprambient pressures at 45 kPa. In contrast, northern fur seals produced no detectable pressure measurements. Steller sea lions have a broader feeding repertoire than northern fur seals, which likely enables them to feed on a greater variety of prey, in more diverse habitats. Based on the basal phylogenetic position of northern fur seals, craniodental morphological data of the Callorhinus lineage, and the performance data provided in this study, we suggest that northern fur seals may be exhibiting their ancestral feeding mode.
摄食性能研究可以解决与摄食生态学和进化相关的问题。我们目前对水生哺乳动物摄食机制的了解很有限。因此，我们对5只北海狗（Eumetopias jubatus）和6只北海狮（Callorhinus ursinus）的摄食运动学和性能进行了表征。我们检验了以下假设：这两个物种都以吸力作为主要摄食模式，并且快速张口与吸力产生有关。北海狗以吸力作为主要摄食模式，但也使用咬食摄食模式。相比之下，北海狮只使用咬食摄食模式。北海狗的运动学特征均表明其通过吸力摄食（即小张口度、小张口角度、舌骨舌器大幅下降和唇部收缩）。然而，用张口角度张开速度（GAOV）测量的北海狗的张口速度相对较慢。与北海狗相比，北海狮的GAOV极快，但其运动学特征表明其采用咬食摄食模式（即与北海狗相比，北海狮表现出更大的张口度、更大的张口角度和舌骨舌器的最小下降）。北海狗在45 kPa时产生低于和高于环境的压力。相比之下，北海狮没有检测到压力测量值。北海狗的摄食方式比北海狮更广泛，这可能使它们能够在更多样化的栖息地以更多种类的猎物为食。基于北海狮在系统发育中的基础位置、北海狮谱系的颅齿形态数据以及本研究提供的性能数据，我们认为北海狮可能表现出其祖先的摄食模式。
