武夷科学

<正> 眼镜蛇 Na ja na ja atra 为外温动物,其生理功能状况必然受环境温度的强烈影响,消化生理也不例外。从摄取能量物质过程和生态习性的角度看,眼镜蛇的生理温度可划分为摄食温区和戒食温区。但区界温度是多少,尚未见具体数据。此外,温度对其消化曲线的影响如何也未见报道。当然蛇自身生理节律性对消化也有影响。本实验仅从不同环境温度探讨上述存在问题。弄清这些问题在理论上可丰富眼镜蛇消化生理学内容,在实践上对选择最佳温度投食饲养眼镜蛇也有指导作用.

36 healthy cobras with the length of 84-86cm.(from mouth to anus)and the weight of 188-260g.were kept in the snake garden for 2 months.In June,when the atmospheric tem- perature was 25-28℃,we weighed every cobra before and after its taking in the weighed toads,then divided them into 4 groups at random and put them in the biochemistry incuba- tors at the temperature of 15℃,20℃,25℃ and 35℃,respectively.Among them,the 15℃ and 20℃ groups contained 12 cobra each,and the 25℃ and 35℃ ones 6 each.They were surveyed once every 12 hours for the following points:(1)To count the vomiting rates of the cobras vomiting their indigested toads and compare these rates with the vomiting rates at different temperatures to establish the demarcation line of temperature ranges.At the sametime,we calculated the staying time of the toads in the alimentary canal of the sankes and studied the relation between such duration of time and the weight of the swallowed toads to make clear whether there were any definite relations between vomiting and the sizes of the toads.(2)As for the cobra with good digestion,we took the measures of continually weighing them at an interval of 6,12 or 24 hours,so as to calculate the percentage of daily digestive residue and to draw up the digestive curve.At last,we matched it with logistic curve and compared the slope of the curves at 20℃,25℃ and 35℃ to confirm the influence of temperature on cobra's diges- tive curve.The results came out as follows: (1)There is no significant cirtial temperature value between food-taking temperature range and non-food-taking temperature range.The transition temperature is around 20℃. (2)The food-taking-temperature range is from 25℃ to 35℃,where the cobra not only took in food but also digested it completely.The non-food-taking temperature is 15℃.At 15℃,the cobra was not able to take in food,even if at 25℃,the taken food would all be thrown out. (3)The vomiting speed exhibits Iittle association with the sizes of eaten toads. (4)The cobra digestive curve is logistic curve.The slope of the digestive curve at 35℃ is very significantly larger than at 25℃ and 20℃.But there is no significant differences in the slope of cobra digestive curve between 20℃ and 25℃(b_35℃1.673,b_25℃=0.6285, b_20℃=0.6505).The digestive speed at 35℃ is very significantly quicker than at 25℃ and 20℃.