## 3 Results
### Changes in Observed Behavior and Morphology  
During the experiment, the behavioral and morphological alterations in snails exposed to varying quantities of Cu, Zn, Cd, Pb and Ni were observed. When the snails were \begin{table}
\begin{tabular}{c c c c c c} \hline  & **Snails** & **Juvenile** & **Juvenile** & **Adult** & **Adult** \\ \cline{2-6}  & **Periods** & **48 h** & **72 h** & **48 h** & **72 h** \\ \hline Cd & LC\({}_{50}\) & 3.67 & 2.15 & 24.73 & 11.71 \\  & SE & 0.52 & 0.40 & 3.64 & 1.78 \\  & LCL & 2.63 & 1.34 & 17.38 & 8.07 \\  & UCL & 4.71 & 2.96 & 32.09 & 15.35 \\ \hline Cu & LC\({}_{50}\) & 0.94 & 0.50 & 3.10 & 1.84 \\  & SE & 0.21 & 0.28 & 0.56 & 0.58 \\  & LCL & 0.53 & \(-\)0.10 & 1.98 & 0.68 \\  & UCL & 1.36 & 1.09 & 4.22 & 3.00 \\ \hline Ni & LC\({}_{50}\) & 4.77 & 3.01 & 10.73 & 6.88 \\  & SE & 1.16 & 1.32 & 1.37 & 1.42 \\  & LCL & 2.42 & 0.32 & 7.95 & 3.90 \\  & UCL & 7.12 & 5.70 & 13.50 & 9.85 \\ \hline Zn & LC\({}_{50}\) & 30.16 & 11.36 & 57.99 & 26.97 \\  & SE & 4.81 & 3.50 & 8.22 & 5.32 \\  & LCL & 20.43 & 4.19 & 41.18 & 15.84 \\  & UCL & 39.90 & 18.52 & 74.80 & 38.10 \\ \hline Pb & LC\({}_{50}\) & 10.99 & 8.35 & 17.24 & 11.45 \\  & SE & 1.29 & 1.14 & 1.99 & 1.31 \\  & LCL & 8.39 & 6.04 & 13.22 & 8.80 \\  & UCL & 13.59 & 10.66 & 21.25 & 14.09 \\ \hline \end{tabular}
\end{table} 
Table 1: Comparisons of the LC\({}_{50}\) values (mg/L) of Cd, Cu, Ni, Pb and Zn in both juveniles and adults _P. Pomaexposed to lower concentrations of these metals, they could move up and down, stretch their bodies from their shells, and attach themselves to the wall of the plastic container. The majority of the snails survived the experimental period, which corresponded well with the findings of [PERSON] and [PERSON] [28]. At moderate concentrations of these metals, the snails secreted mucus with a decreased movement rate. They were inert, incapable of attaching their feet or closing their operulum, and unable to retract their bodies into their shells. The bodies of the snails were mostly exposed in plastic containers. They produced a great deal of mucus, and their feet stretched from their shells but could not retract. Generally, they sunk to the bottom of the plastic containers and became immobile. The crawling or movement of snails during the experimental periods in an attempt to escape the experimental aquaria was a major drawback of this static toxicity test. As a result, high metabolic rates may have resulted in a large uptake of toxicants at that time, or the snails' activity in a starving condition may have decreased their resistance to toxicants. The size and age of the animals utilized in the toxicity test were additional variables that affected the LC\({}_{50}\) values. It is well known that as an animal ages, its toxicity and tolerance to metals diminish. Cd and Cu concentrations in the soft tissues of freshwater clams have been found to similarly decrease with increasing age [29]. Young snails may be more sensitive to some metals due to their increased accumulation rates. [PERSON] and [PERSON] [30] revealed that juvenile _Physa gyrina_ snails were three times as sensitive to Cd as their mature counterparts. Therefore, larger animals have greater resistance than smaller ones. The present study, using snails of two different sizes, confirmed the predicted result. On the other hand, these snails have an operulum to protect them when the water around them becomes toxic. In the present experiment, _P. insularum_ developed a white slime when they were exposed to high concentrations of Cd (19.98 mg/L) and Cu (4.08 mg/L). Based on the physiological reactions, [PERSON] [31] discovered that _Biomphalaria glabrata_ was more resistant to heavy metals after 24 h of exposure. According to their observations, snails sank to the bottom with their operulum closed, expelled bubbles and slowed down their metabolic processes. When exposed to high levels of Cd and Cu, the snails could not adhere to the tank walls because the metals impede cell dynamics and injure the snails' tissues and cells [32].