دراسة لبعض الجوانب الحياتية والمظهرية للقوقع الأفريقي الأرضي Achatina fulica (Férussac, 1821)

Study of some Biological and Morphological Aspects of the Land African Snail Achatina Fulica (Férussac, 1821)

A study was conducted on some biological and morphological aspects of the Achatina fulica (Ferussac, 1821), which is one of the giant land snails that is not endemic to our country (invasive), for one year extending from May 2023 to May 2024. The results of the study included the following:
The study included an accurate description of the appearance of the giant African snail A.fulica and its parts from the outside to the inside. The shell (the hard part) is the largest basic part of the African snails body. The standard dimensions of the shell were studied and it was found that the highest average length of the African snail is 13.95 cm and a width of 7.35 cm. And the average length and width of the shell opening ( 3.2 , 4.8 ) cm, respectively, and the length and width of the right lip (1.2 , 4.2 ) cm, respectively.
The outer layer, which represents the tissue of the shell, is rough and has long vertical grooves on the annular unit, while the inner layer is smooth, smooth, periosteal, pearly, and the distribution of the internal air spaces of the chambers was in accordance with the internal visceral mass (the wet part).
The growth rings are related to the size and age of the snail. They begin with two rings immediately after hatching and end with eight rings during the rest of the life stages. The rings are more pronounced during favorable growth conditions and advancing age.
According to the study, the sufficient time period for incubating the eggs, given the availability of appropriate environmental factors, is nine days, with the tenth day being the day the egg hatches. The sizes, colors, and weights of the eggs vary according to the advanced embryonic development within them, and what results from hatching are individuals of two colors (albino and brown).
The results also showed that the fertility of the African snail is proportional to the length of the mother snail’s shell and the number of eggs laid by it. The highest and lowest number of eggs was (99 . 421 ) eggs laid by mother snails with a shell length of (10.1 , 15.2) cm, respectively, in When fertility had a fluctuating relationship with the weight of the mother conch.
Typical environmental measurements for the African snail were determined, and the ideal air and soil temperature (20° – 25° ),(22° – 26°) respectively , humidity (70% – 90% ), electrical conductivity (1.5) ds/m , pH (8), and rates of each of (potassium ions, magnesium, sodium, calcium, chlorine) (110 , 40.5 , 215.2 , 185 , 1100 )PPM respectively, while the soil texture was sandy and loamy soil.
The study showed that the African snail resorts to group behavior in coexistence, especially in the initial stages of its life, and that it forms a special plug to close the shell hole in the event that appropriate conditions are not available for it.
The wet and dry weight, ash and dry weight free of ash were calculated and their relationship with age group was shown, which indicated a strong positive relationship between overall weights and age during early development, but the rate of increase decreases significantly with the maturity of the snails.
Secondary production of African snails A.fulica was estimated according to age groups. in terms of the dry and ash-free weight, they are
(68.01g/m2/years) and (114g/m2/years) respectively.