Abstract
In an attempt to elucidate the role of calcium in the life of the edible Achatinid snail, Limicolaria flammea (Miller) I investigated short and long term effects of calcium added to the food. The short term experiments lasted for 18, 30 and 32 weeks respectively, while the long term experiment to determine life time utilization of calcium carbonate lasted for 15 months. In the short term experiments, hatchlings were divided into densities of one, ten and 50 snails. In the 10 snail group, there was a positive correlation between calcium provision, body weight (t test, p < 0.01; r = 0.96, p < 0.0001) and shell length (t test, p < 0.01; r = 0.96, p < 0.00001). There was also a positive correlation between increase in shell length and availability of calcium in the 1 snail group (t test, p< 0.01; r = 0.99, p < 0.00001). In the 50-snail group, the correlation was positive for shell length of the snails (t test, p < 0.05; r = 0.99, p < 0.0001) and body weight (t-test, p < 0.05; r = 99, p < 0.00001). Mortality was very high in the snails deprived of calcium and they did not produce eggs. In the long term experiment, there were three feeding peaks in L. flammea. In the first feeding peak, amount of food and calcium ingested by the snails increased in the first three months of life. The second feeding peak occurred at six months of age, while the last occurred at 10 months of age. The amount of calcium ingested during the second peak decreased gradually in the 4th and 5th month. The amount of calcium ingested was lowest during the 3rd feeding peak. The period of highest weight gained by the snails was between the 1st and 6th month and then dropped at between six and 12 months of age which corresponds to the period of egg production. There were also three peaks of egg production; the first was between six and eight months (535 eggs), the second at between 10 and 11 months (350 eggs) and the third at 13 to 14 months (310 eggs) respectively.
Highlights
Dietary calcium is an essential nutrient for growth and reproduction and construction of the shell in terrestrial gastropods (Boycott 1934, Wagge 1952, McKillop and Harrison 1972, Crowell 1973, Tompa and Wilbur 1977, Peake 197 insoluble salts of calcium carbonate was one of the major steps in colonization of land by various groups of gastropods (Tompa 1980)
This paper investigates life time utilization of calcium and the influence of omitting calcium carbonate from the diet on the growth and fecundity in Limicolaria flammea (Müller)
It is clear from the figure that, the form of growth is similar in the experiment and control groups, lack of calcium has a profound negative effect on snail growth from the very start of life
Summary
Dietary calcium is an essential nutrient for growth and reproduction and construction of the shell in terrestrial gastropods (Boycott 1934, Wagge 1952, McKillop and Harrison 1972, Crowell 1973, Tompa and Wilbur 1977, Peake 197 insoluble salts of calcium carbonate was one of the major steps in colonization of land by various groups of gastropods (Tompa 1980). Snail hatchlings need to build a strong shell soon after emergence and the parental effort extends in some species to providing calcium-rich faeces or coating the eggs with a layer of calcium-rich soil (Tompa 1980). Some snails select sites for oviposition which provide supply of calcium after emergence (Beeby and Richmond 1988). Provision of calcium carbonate and nutrients to the shell is the most common form of parental investment (Baur 1994) and among the gastropods a variety of strategies are used to ensure sufficient calcium for the hatchlings to build a shell after emergence (Beeby and Richmond 2001). This paper investigates life time utilization of calcium and the influence of omitting calcium carbonate from the diet on the growth and fecundity in Limicolaria flammea (Müller)
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