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The
Common Periwinkle (Littorina littorea)
is adapted to living in the intertidal at all levels [www.marlin.ac.uk]. Snails require moisture to forage for food
along the rocks of the rocky shore. The question is do they need that moisture
to come from the ocean, dew or rainfall?
I and my fellow students collected Littorina
littorea at the North Eastern Marine research lab in Nahant, Massachusetts.
I observed individuals on site and in a
laboratory setting. Samples were put in lined petri dishes or bins, depending
on location. I exposed the samples to a
treatment of fresh and salt water spray for set periods of time. I recorded the reactions and behaviors of the
snails on paper, by video, or pictures. There
was no movement from the samples when exposed to freshwater. Almost all
individuals moved when exposed to salt water. A chi2 test yielded a p-value of 0.0000 when I
compared movement to treatment. Along the rocky shore of Nahant
there are many small tide pools that capture the ocean water. Marine snails will prefer to be in a marine
environment rather than fresh or brackish when they can help it. This short
study shows that during periods of heavy rain L. littorea does not
forage for food.
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