The golden apple snails (P. canaliculata) were obtained from Ozamis City and
Plaridel, Misamis Occidental. A total of 60 specimens were utilized comprising of 30
females and 30 males for each population. Map showing the study area is shown in Shells were photographed by a digital camera. Images of the shell were in the
same position with the columella at 90 of the x-axis in an aperture view or in the
orientation in which the apex is visible. Obtained images were then subjected to
geometric morphometric methods. Digital images (ventral, dorsal and top view) were
taken for each sample using a standardized procedure (Fig. 2). The shell of the apple
snail is spherical or heliciform or elongate ovate shell form having three to five
sutures with wide oval or circular aperture. It has no siphonal canal and the outer lip
of the aperture is not reflected.Shell shape was studied using a landmark-based methodology that eliminates the effect of variation in the location, orientation, and scale of the specimens. Twenty one anatomical landmarks located along the outline of the ventral/apertural (Fig. 2a) portion of the shell and seventeen anatomical landmarks along the dorsal (Fig. 2b)portion of shell were defined and used. Obtained digitized images of the snail’s shell were then outlined with sample points around its contour in order to get the x and ycoordinates. This was made possible using an image analysis and processing softwaretps Dig freeware 2.12 which facilitates the statistical analysis of landmark data from digitized images (Rohlf, 2008a).