Okamoto Kohei, Mori Akira, Ikeda Yuzuru
1 Department of Zoology, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan.
2 Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan.
Zoolog Sci. 2015 Aug;32(4):336-44. doi: 10.2108/zs140288.
We examined the effects of predator-prey distance (PPD) and trajectory of the predator on the body patterns that the pharaoh cuttlefish, Sepia pharaonis, shows in response to a predator. A model predator moving in three different trajectories was presented to the cuttlefish: T1, approached the cuttlefish but bypassed above; T2, approached directly toward the cuttlefish; T3, bypassed the cuttlefish both vertically and horizontally. We divided the body patterns that the cuttlefish expressed into seven categories, i.e., "uniform light", "disruptive", "center circle", "dark square", "vertical stripe", "all dark" and "eyespots". In T1, the number of individuals that showed "dark square" increased as the model approached the cuttlefish, whereas the number of individuals that showed "disruptive" decreased. In T2, the number of individuals that showed "all dark" and "eyespots" increased as the model approached the cuttlefish. In T3, the number of individuals that showed "dark square" and "vertical stripe" increased as the model approached the cuttlefish, and it tended to decrease as the model receded from the cuttlefish. These results demonstrate that S. pharaonis changes its body patterns according to PPD and the trajectory of the predator, which would affect predation risk and/or predator perception.
我们研究了捕食者与猎物的距离（PPD）以及捕食者的轨迹对法老乌贼（Sepia pharaonis）针对捕食者所呈现的身体图案的影响。向乌贼展示了一个以三种不同轨迹移动的模型捕食者：T1，靠近乌贼但从上方绕过；T2，直接朝着乌贼靠近；T3，在垂直和水平方向上都绕过乌贼。我们将乌贼表现出的身体图案分为七类，即“均匀浅色”、“干扰性”、“中心圆圈”、“深色方块”、“垂直条纹”、“全深色”和“眼斑”。在T1中，随着模型靠近乌贼，表现出“深色方块”的个体数量增加，而表现出“干扰性”的个体数量减少。在T2中，随着模型靠近乌贼，表现出“全深色”和“眼斑”的个体数量增加。在T3中，随着模型靠近乌贼，表现出“深色方块”和“垂直条纹”的个体数量增加，而随着模型远离乌贼，其数量趋于减少。这些结果表明，法老乌贼会根据PPD和捕食者的轨迹改变其身体图案，这会影响捕食风险和/或捕食者的感知。
