Classification
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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