Shell Measurements and Growth Rate of the Two Terrestrial Snails Eobania vermiculata (muller) and monacha cartusiana(Muller) (Mollusca: Helecidae) under Laboratory Conditions

摘要

Both of the land snail species Eobania vermiculata (Muller) and Monacha cartusiana (Muller) are mainly nocturnal as hide during day light hours, and herbivorous which fed only on different host plants. Laboratory measurements on collected snails of both species indicated that the weight, shell diameter, shell height, as well as aperture area differed according to species, host plant and locality. Thus, the shell diameter of newly hatched juveniles of M. cartusiana averaged 1.7 ± 0.2 mm while of E. vermiculata averaged 3.0 ± 0.1 mm. while they are weightless in the same time.The growth rate of M. cartusiana reached its maximum 38.7% in the fourth month after hatching, when the shell diameter averaged 7.8 ± 2.0 mm and its weight was 0.16 ± 0.1 gm., while that of E. vermiculata was 50.3 % during the first month after hatching with an average of shell diameter 6.3 ± 1.1 mm and 0.07 ± 0.04 gm. weight.The shell diameter remains stable at an average of 11.8 ± 0.4 mm from the sixth month for M. cartusiana and from the eighth month with an average of 26.5 ±1.7 mm for E. vermiculata. The maximum weight of M. cartusiana was 0.34 ± 0.1 during the sixth &seventh month then decreased in eighth month. On the other hand, the maximum weight was 4.5 ± 0.9 gm. for E. vermiculata in the eighth month then decreased in the ninth month.