Prey Discrimination Mechanisms of Chinese Crocodile
Lizard (Shinisaurus crocodilurus)

In order to understand the foraging behavior and ecology of Chinese crocodile lizard (Shinisaurus crocodilurus), we studied its prey discrimination mechanisms through two series experiments. In the first experiment, the swabs were dampened by deionised water, cologne, smashed earthworm (Pheretima sp.) and smashed tenebrio (Tenebriomolitor L.) as the chemical cues and observed the response of 11 Chinese crocodile lizard. 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 and the number of tongue-flicks in response to tenebrio and earthworm stimuli were significantly higher than that to cologne and deionized water (Wilcoxon test, all P<0.001). It indicate that the Chinese crocodile lizard can discriminate food and non-food stimulus. In the second experiment, we observed the responses of Chinese crocodile lizard to the following cues: (A) blank utensil, (B) the utensil was wetted by smashed earthworm, (C) the alive earthworm was sealed in the utensil, (D) alive earthworm was kept in the open utensil. Each individual was tested 5 times in each cue. Results showed that the Chinese crocodile lizard 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（only visual cue）and in cue D （visual and chemical cue）were significantly high than in cue B（only chemical cue）（all P<0.001). Without visual cue, the dealing time and investigation frequency were significantly high than in cue A (blank)(all P<0.001). Under the same visual cues, only dealing time in cue D was higher than that in cue D (Z=3.95, P<0.001), but investigation frequency and attack frequency were not 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.