室内飼育におけるチリメンカワニナの成長と産仔数

概要

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Growth and number of newborns in Semisulcospira reiniana reared during 48-51 months under the three different temperature conditions in the laboratory were studied. The newborns, which were produced in July and August 1986, grew up to 8-9mm in mean shell diameter by the age of 1, 11-12 mm by the age of 2, 12-13 mm by the age of 3, 13-14mm by the age of 4. The maximum size of S. reiniana reared at 21±2℃ is 16.4 mm in shell diameter, 45.1 mm in shell height, 7.4 g in wet weight with shell. When the size of mature snails grown up at each aquarium reached over 9 mm in mean shell diameter, 20-22 mm in mean shell height, 0.9-1.0 g in wet weight with shell at the 12-14th months since their births, the production of newborns was begun. Birth of newborns occurred at a water temperature between 12℃ and 28℃. Large number of newborns were produced at a water temperature between 20℃ and 28℃. Number of newborns during a month per female is estimated 10-38 individuals at a water temperature between 20℃ and 28℃. Large number of newborns during a year were produced by mature female larger than 10 mm in mean shell diameter at 2-3 ages. Optimum temperature for growth is lower than for production of newborns. Under the high water temperature condition, maximum size of snails was small and survival rate was low, but production of newborns was increased.
1992-07-31