Tuesday, August 5, 2008

Lovells Island - From Periwinkles to Snails

On the morning of August 4, Monday, we traveled by boat to Lovells Island, (http://www.nps.gov/archive/boha/parkmaps/lovells.pdf), an island located in Quincy Bay. Along the walking path going from south to north, the group encountered land snails along the way around 10:40am.

These snails were found mostly on or under leaves and out of the sun. They appeared to be found in groups in certain areas of the island and had much more varied coloring than the perwinkles discovered later in the day. The trees the snails were found in were predominantly sumac trees ranging from approximately 6' to 15' feet tall.

The class traveled to the north end of the island at low tide at approximately 11am, August 5th, 2008. We passed through what was an old marsh that had predominantly old mussel shells, there were periwinkle shells, though rare. The shells were only a couple inches deep.

One of the first animals encoutered was a wharf crab. The crabs were not found on shore and commonly appeared when the bottom of rocks were lifted.

The low tide allowed easy access to groups of common periwinkles. The perwinkles sampled were found on hard rock surfaces in water approximately two to three feet deep and 20-40 feet into the water.

Two periwinkles were selected for a experiments. Both were healthy and alive. The first was to examine how a perwinkle would gain a footing if was left on it's back. The perwinkle extended itself slowly using the weight of it's body to cause the shell to roll over at which point the perwinkle was able to regain adhesion to a solid surface in a few seconds.
Another experiment was done to test for survivability in fresh water. One was placed back into the original sea water while an other was put into a fresh water aquarium. The fresh water caused the periwinkle to become unresponsive almost immediately.