鳄蜥的食物识别机制

Prey Discrimination Mechanisms of Chinese Crocodile Lizard (Shinisaurus crocodilurus)

鳄蜥(Shinisaurus crocodilurus)食物识别机制的研究,对进一步了解鳄蜥的捕食行为和生态学习性有重要意义。使用棉棒分别沾上去离子水、香水、黄粉虫(Tene briomolitor L.)和蚯蚓(Pheretima sp.)的气味(蚯蚓和黄粉虫处死后绞碎以便于棉花棒蘸上),观察11只鳄蜥对4种化学刺激的反应,每个个体对每种刺激均进行24次实验重复。实验结果显示:鳄蜥对4种刺激均有反应,对黄粉虫和蚯蚓刺激的舔舌次数显著高于香水和去离子水的舔舌次数(Wilcoxon test,所有P<0.001),表明鳄蜥能检测以及识别控制刺激和食物刺激。再又对鳄蜥进行4种处理实验:(A)空白对照;(B)蚯蚓气味;(C)密封着的活蚯蚓;(D)活蚯蚓。每个个体每种处理均进行5次实验。结果显示:鳄蜥在不同处理下的行为持续时间、探究频次和攻击频次有显著差异(Friedman test,所有P<0.001)。鳄蜥在仅有视觉刺激出现的处理C以及既有化学刺激又有视觉刺激的处理D比仅有化学刺激的处理B在持续时间、探究频次和攻击频次上都显著要高(所有P<0.001)。在无视觉刺激的条件下,鳄蜥在处理B的行为持续时间以及探究频次均显著高于处理A的(所有P<0.001);而在视觉信息相同的条件下,鳄蜥在处理D中仅行为持续时间显著高于处理C(Z=3.95,P<0.001),而探究频次以及攻击频次无显著差异(前者Z=1.53,P=0.13;后者Z=1.10,P=0.27)。结果表明,鳄蜥主要利用视觉捕食,化学感觉有辅助作用。鳄蜥这种食物识别机制可能与捕食模式和种系发生有关,也可能受食物的影响。

To understand the foraging behavior and ecology of the Chinese crocodile lizard （Shinisaurus crocodilurus）, we studied prey discrimination mechanisms through two series of experiments. The first experiment used swabs dampened with deionised water, cologne, macerated earthworm （Pheretima sp.） and macerated tenebrio （Tenebriomolitor L.） as chemical cues and the response of 11 Chinese crocodile lizard was observed. Each individual was tested 24 times to each stimulus. The results showed that all individuals of Chinese crocodile lizard responded to the swabs by tongue flicking. The number of tongue-flicks in response to the tenebrio and earthworm stimuli was significantly higher than that to the cologne and deionized water （Wilcoxon test, all P〈0.001）. This indicates that the Chinese crocodile lizard can discriminate food and non-food stimuli. In the second experiment, we observed the responses of Chinese crocodile lizard to the following cues： （A） blank utensil, （B） utensil treated with macerated earthworm, （C） a live earthworm sealed in the utensil, （D） a live earthworm placed in the open utensil. Each individual was tested 5 times for each cue. Results showed that the Chinese crocodile lizard response for each cue was significantly different in dealing time, investigation frequency and attack frequency （all P〈0.001）. The dealing time, investigation frequency and attack frequency in cue C （visual cue） and in cue D （visual and chemical cue） were significantly higher than in cue B （chemical cue） （all P〈0.001）. Exclusion of the visual cue, showed the dealing time and investigationfrequency were significantly higher than in cue A （blank） （all P〈0.001）. Under the same visual cues, only dealing times in cue D was higher than that in cue D （Z=3.95, P〈0.001）. But investigation frequency and attack frequency were not significantly different between cue C and D （for former Z=1.53, P=-0.13 for latter Z=1.10, P=-0.27）. These indicate that Chinese crocodile lizard rely more on visual cues to discriminate prey than on chemical cues. The prey discrimination mechanisms of Chinese crocodile lizard may be related with foraging mode, phylogeny and prey.