Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA 95060, USA.
Waikiki Aquarium, University of Hawai'i at Manoa, Honolulu, HI 96815, USA.
Integr Comp Biol. 2020 Aug 1;60(2):425-439. doi: 10.1093/icb/icaa075.
The ability to expand the behavioral repertoire past seemingly rigid morphological features enables animals to succeed in a variety of ecological contexts. The integration of morphology, performance, and behavior produces diverse animal feeding strategies. These different strategies reflect trade-offs between specialization, prey choice, and energetic expenditure, which have important consequences for understanding individual and population-level flexibility in response to environmental change. Here we examined the feeding strategies used by the Hawaiian monk seal (Neomonachus schauinslandi), an endangered marine predator. We tested how Hawaiian monk seal feeding strategies change in response to ecological context, specifically prey size and prey location at different depths. Seven captive Hawaiian monk seals were fed five prey types across a continuum of sizes, and prey were presented at three depths to represent surface, pelagic, and benthic feeding. Hawaiian monk seals used suction feeding and biting strategies, and these strategies were associated with significant differences in behavior and kinematic performance. Hawaiian monk seals used suction feeding most frequently when targeting small to medium prey (0-79% of the seal's head length) but switched to biting when consuming large prey (>80% of the seal's head length). These results demonstrate that prey size drives the transition between suction feeding and biting strategies. Seals also switched strategies based on prey position in the water column, primarily using suction feeding when prey were benthic and pelagic, and biting when prey were at the water's surface. Overall, suction feeding was three to five times faster than biting, required a smaller gape, and used fewer jaw movements, allowing seals to quickly consume numerous small to medium sized prey. In contrast, biting was slower but resulted in the ability to target larger, potentially more energy rich prey. Our results show that Hawaiian monk seals exhibit flexibility in their use of different feeding strategies, which likely facilitates increased foraging success when feeding in spatially and temporally dynamic marine environments.
动物具有超越形态特征的行为能力，使其能够在各种生态环境中取得成功。形态、表现和行为的整合产生了多样化的动物摄食策略。这些不同的策略反映了专业化、猎物选择和能量消耗之间的权衡取舍，这对理解个体和种群水平对环境变化的灵活性具有重要意义。在这里，我们研究了夏威夷僧海豹（Neomonachus schauinslandi）所采用的摄食策略，这是一种濒危的海洋捕食者。我们测试了夏威夷僧海豹的摄食策略如何根据生态环境发生变化，特别是猎物的大小和不同深度的猎物位置。七只圈养的夏威夷僧海豹在一系列大小的连续体上被喂食五种猎物类型，并且在三个深度上呈现猎物，以代表水面、远洋和海底摄食。夏威夷僧海豹使用抽吸和咬噬策略，这些策略与行为和运动学表现的显著差异相关。当目标是小至中等大小的猎物（海豹头部长度的 0-79%）时，夏威夷僧海豹最常使用抽吸进食，但在消耗大型猎物（>80%的海豹头部长度）时则切换为咬噬。这些结果表明，猎物大小驱动了抽吸和咬噬策略之间的转变。海豹还根据水柱中的猎物位置切换策略，当猎物位于海底和远洋时主要使用抽吸进食，而当猎物位于水面时则使用咬噬。总体而言，抽吸进食比咬噬快三到五倍，需要的张口更小，使用的下颚运动更少，使海豹能够快速消耗大量小至中等大小的猎物。相比之下，咬噬较慢，但可以针对更大、潜在更有能量的猎物。我们的研究结果表明，夏威夷僧海豹在使用不同的摄食策略方面表现出灵活性，这可能有助于它们在空间和时间上动态的海洋环境中增加觅食成功的机会。
