Waltzek Thomas B, Wainwright Peter C
Section of Evolution and Ecology, University of California, Davis, California 95616, USA.
J Morphol. 2003 Jul;257(1):96-106. doi: 10.1002/jmor.10111.
The New World cichlids Petenia splendida and Caquetaia spp. possess extraordinarily protrusible jaws. We investigated the feeding behavior of extreme (here defined as greater than 30% head length) and modest jaw-protruding Neotropical cichlids by comparing feeding kinematics, cranial morphology, and feeding performance. Digital high-speed video (500 fps) of P. splendida, C. spectabile, and Astronotus ocellatus feeding on live guppy prey was analyzed to generate kinematic and performance variables. All three cichlid taxa utilized cranial elevation, lower jaw depression, and rotation of the suspensorium to protrude the jaws during feeding experiments. Extreme anterior jaw protrusion in P. splendida and C. spectabile resulted from augmented lower jaw depression and anterior rotation of the suspensorium. Morphological comparisons among eight cichlid species revealed novel anterior and posterior points of flexion within the suspensorium of P. splendida and Caquetaia spp. The combination of anterior and posterior loosening within the suspensorium in P. splendida and Caquetaia spp. permitted considerable anterior rotation of the suspensorium and contributed to protrusion of the jaws. Petenia splendida and C. spectabile exhibited greater ram distance and higher ram velocities than did A. ocellatus, resulting primarily from increased jaw protrusion. Petenia splendida and C. spectabile exhibited lower suction feeding performance than A. ocellatus, as indicated by lower suction-induced prey movements and velocities. Thus, extreme jaw protrusion in these cichlids may represent an adaptation for capturing elusive prey by enhancing the ram velocity of the predator but does not enhance suction feeding performance.
新世界丽鱼科鱼类华丽佩滕丽鱼（Petenia splendida）和卡克塔丽鱼属（Caquetaia spp.）拥有极其可伸展的颌骨。我们通过比较摄食运动学、颅骨形态和摄食性能，研究了颌骨极度（此处定义为大于头长的30%）和适度突出的新热带丽鱼科鱼类的摄食行为。分析了华丽佩滕丽鱼、美丽卡克塔丽鱼（C. spectabile）和眼点丽鱼（Astronotus ocellatus）捕食活孔雀鱼猎物时的数字高速视频（500帧/秒），以生成运动学和性能变量。在摄食实验中，所有这三个丽鱼科类群都利用颅骨抬高、下颌压低和悬器旋转来伸展颌骨。华丽佩滕丽鱼和美丽卡克塔丽鱼的颌骨极度前伸是下颌压低增强和悬器向前旋转的结果。对八个丽鱼科物种的形态学比较揭示了华丽佩滕丽鱼和卡克塔丽鱼属悬器内新的前后弯曲点。华丽佩滕丽鱼和卡克塔丽鱼属悬器内前后松弛的结合使得悬器能够进行相当大的向前旋转，并有助于颌骨的伸展。华丽佩滕丽鱼和美丽卡克塔丽鱼比眼点丽鱼表现出更大的咬距和更高的咬速，这主要是由于颌骨伸展增加所致。如较低的吸力引起的猎物移动和速度所示，华丽佩滕丽鱼和美丽卡克塔丽鱼的吸食性能低于眼点丽鱼。因此，这些丽鱼科鱼类的极度颌骨前伸可能代表了一种适应方式，即通过提高捕食者咬速来捕获难以捉摸的猎物，但不会提高吸食性能。
