Biology of the perforate dome snail, Ventridens Demissus (Gastropoda: Zonitidae) from Seabrook, Texas



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The perforate dome snail (Ventridens demissus) is a terrestrial gastropod in the Zonitidae family. In this study I observed morphological variance, shell strength, reproductive behavior, egg size, hatchling growth, microbial gut content and species distribution of V. demissus. Shell height, width, and distance from aperture to callus were measured using a digital caliper. Whorl count was measured visually under a dissecting microscope. Shell strength was observed by placing shells between two metal plates and applying force in 0.1N increments until shell failure. Reproductive behavior was observed visually. Egg width was measured using digital calipers. Hatchling growth was measured by shell width using digital calipers every week. DNA extraction and NGS were used to examine microbial gut content. GEOLocate and DIVA-GIS software were used to create a point distribution map from museum records. Shell measurements were 5.66 mm ± 0.69 mm height, 8.19 mm ±0.71 mm width, 5.0 ± 0.5 whorls, and 1.94 mm ± 1.27 mm aperture to callus. Shell width was significantly positively correlated with shell height (R2 = 0.73, p<0.05) and whorl count (R2 = 0.18, p<0.05). Shell width was not significantly correlated with lamellar callus distance (p=0.53). Mean shell crushing strength was 4.6 N ± 2.5 N. Shell strength was not significantly correlated with shell width (p=0.32). I observed face-to-face simultaneous mating behavior in one couple. Average egg width (n=321) was 1.53 mm ± 0.12 mm. Hatchling growth rate was y =0.0632x + 1.4183. Mycoplasma, Peanibacillus, Simkaniaceae, and Enterobacteria were the four most abundant microbes in gut content. Species distribution is assumed to be from the southeastern to northeastern U.S. with a concentration in the Appalachian region. Information gathered from this study will fill data gaps in land snail literature and can be used to better understand evolution and systematics of land snail communities.