Identification and Reporting

The following are the characteristics of the NZMS found in the western United States:

Color: Shell-dark to very dark brownish, the head, foot, and  mantle are colored dark with melanin pigments.

Size: 5-12 mm. The snail is usually 4–6 mm in length in USA populations, but grows to 12 mm in its native range (Zaranko et al. 1997; Levri et al. 2007). The periostracum (outer layer of the shell) is usually thin, and is often colored.

Shell: dextral (if held tip down and opening toward you, the opening is on the left), the shell has about 5.5 strongly convex whorls (the North American strain lacks a ridge or processes on the whorls). The shell opening is roundish to somewhat ovate as opposed to strongly ovate or lunate. There is an attached operculum which can close off the opening. The operculum is a kind of shell door that the snail can close to seal its shell shut when it feels threatened.

Animal tissue: squashes under low power microscopy show pale to medium yellowish embryos contrasting with much darker parental tissues. Embryos possess eye spots.

The paired eyes are photoreceptors but are not capable of forming an image.

Identified NZMS? Report it using this this form