Shell Description
The shell of Potamopyrgus antipodarum is elongated and it has dextral coiling. The shell has 7 or 8 whorls. Between whorls are deep grooves.
This is an operculate snail, meaning it has a 'lid' that can seal the opening of its shell. The operculum is thin and corneus with an off-centre nucleus from which paucispiral markings (with few coils) radiate. The aperture is oval and its height is less than the height of the spire.
Some morphs, including many from the Great Lakes, exhibit a keel in the middle of each whorl; others, excluding those from the Great Lakes, exhibit periostracal ornamentation such as spines for anti–predator defense.
Shell colors vary from gray and dark brown to light brown.
The average height of the shell is approximately 5 mm ( in); maximum size is approximately 12 mm ( in). The snail is usually 4–6 mm in length in the Great Lakes, but grows to 12 mm in its native range.
Read more about this topic: New Zealand Mud Snail
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