Asymmetrical Plasticity of an Intertidal Snail

Asymetrical developmental Plasticity in an Intertidal Snail

The author of this research was Ron J. Etter. The Nucella Lapilus is a gastropod that resides on both sides of the North Atlanic. In the eastern North Atlantic it extends from Cape St. Vincent in Portugal to Novaya Zemlya. In the Western parts of the North Atlantic it is found from Long Island Sound to Notre Dame. Vertically it ranges from high water tides to low water spring tides. The Lapillus feeds mostly on mussels and barnacles.

There were three main sites used to conduct the experiment. The first site was No Name Point, the second was Bennett Head, and the final was Mackerel Cove. The most areas exposed to waves (No Name, and Bennet) are located in Nahant. Mackerel Cove is sheltered from ocean swells.

The quadrats were “haphazardly” tossed so that the snails would be picked at random. If they just dropped it over an area, it isn’t random. They tested the damage after the drilling to ensure that the snails would still be functional. They did this by allowing the snails to attach to the walls for 30 minutes. If the snails did not move then they would not be used in the experiment. Only 3 of 100 of the snails did not pass this inspection.

In order to test PSA they traced the outline of the foot of the snail, which would have been attached to the glass panels of a five-gallon aquarium. Immediately after they figured out the PSA they tested dislodgement force. Before testing the researchers would tap each snail lightly to make it clamp tightly to the glass. They then inserted a device that would increase the force applied to the snail. The force required to make the snail detach is the dislodgement force. The transplant experiment was created to estimate the changes in PSA between high and low wave energy areas.

The measure of PSA varied by ten percent for hatchlings and juveniles, and four percent for adults. PSA increased with shell length. Also, exposed shore snails produced larger foots. The dislodgement force also increased with shell length. Also, snails from the exposed shored have a higher amount of dislodgement force. The transplant experiment showed that PSA could be changed depending on the environment.

Pe= Juveniles