Domain: Eukaryota
    Stagnicola emarginata fit into the domain Eukaryota because they are multicellular organisms, and have a distinct membrane bound nucleus (Biology online 2008).  A membrane bound nucleus is when the nucleus of a cell is anchored inside of the cell. 

Kingdom: Animalia
    Stagnicola fit into this kingdom because they are heterotrophic.  This means that the animal contains both male and female functional reproductive parts (Hickman et al. 2009).  Animalia also digest food in an internal chamber rather than digesting it extracellular by excreting enzymes.  They also lack cell walls, which plants contain and are motile, can move around freely. They also pass through a blastula stage (Biology online 2008).  This is an early embryo stage in development of animals (Hickman et al. 2009).  Animalia also have specialized sensory organs to recognize and respond to stimuli (Biology online 2008).

Phylum: Mollusca
    The St. Lawrence pondsnails have unsegmented bodies.  Their bodies are also bilateral, which means that if you cut them down the middle the halves will be mirror images, but due to torsion the bodies do not appear to be bilateral.  They are considered to still be bilateral because of their ancestors (Hickman et al. 2009).  They are also covered and protected by a calcareous shell.  Most of the body parts and organs are paired but not repeated longitudinally down the body.  They also have a mantle which encloses their pulmonary cavity, or cavity in which the heart is enclosed (Biology online 2005).

Class: Gastropoda
    Stagnicola emarginata fits into the gastropods because they have spiral shells.  They also move by the means of a flat, muscular foot on their bottom side.  Their heads have one pair of tentacles which is characteristic of the gastropods (Biology online 2005).

Sub-order: Basommatophora (Myers et al. 2008)
    The basommatophores are referred to as the base-eyed snails (Nordsieck 2011) because they have two pairs of tentacles where the eyes reside (Biology online 2005).  The St. Lawrence pondsnail belongs to this group because of that fact.  Another characteristic of the basommotophores is having eggs that stick to rocks and aquatic plants while they are developing (Nordsieck 2011).

Family: Lymnaeidae
    Stagnicola belong to this family because they are freshwater snail that breathes air and have a thin shell.  The shells have an oval shape and are elongated.  The shells also have a large opening with a simple lip in which is why trematode worms find these snails such a good intermediate host for their life cycle (Merriam-Webster 2011).

Genus: Stagnicola
    This snail belongs in this species because it is a common freshwater snail that usually plays intermediate host to trematodes (Merriam-Webster 2011).  It can also be identified by looking at the shell of the snail.  If you look at the aperture, or the opening of the shell, which is much longer than the length of the spire.  The spire contains from the last whorl, a single turn (The free dictionary 2011), to the apex or the highest point of the shell (The free dictionary 2011).  The aperture is also large and round in shape.  The surface of the shell contains microscopic lines. The shape of the whorls are round as well (Digital key to freshwater invertebrates of North Dakota)

Species: Stagnicola emarginata
    To identify the Stagnicola emarginata from its other genera is by the inner lip of the shell.  The inside of the aperture is not brown or purple in color like many other shells.  The aperture is also very plaited.  The adult shell is more than 15 mm in height (G.L. Mackie 1980)

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