Assignment #3: Lovell's Island

Hi Everyone! Yesterday we took a trip to Lovell’s Island where we had the opportunity to observe different elements of marine life which we had yet to see. My observations of the environment are as follows: Date: 8/2/09, Time: between 11am and 4pm, Tide: slightly high to low, Air Temperature: approximately 79 degrees, Water Temperature: approximately 65 degrees, location: salt water off of Lovell’s Island. We began by crossing the island over to the back side and taking a walk on the cobble beach. The assortment of rocks, shells and marine life on the beach made for quite a colorful terrain. We quickly began to observe the different types of shells on the beach, their surfaces as well as their composure and where they may have come from. Quickly we were able to see a large amount of blue muscle shells, what appeared to be old and newer grooved shells and more importantly a good number of periwinkles.

The majority of periwinkles we first found were simply just the shells however as we moved toward the shore we were able to find live periwinkles attached to rocks. Professor Berman stated that these are native periwinkles however scientists tend to believe that these are not really native and that they are Norwegian. The periwinkles feed on algae and plankton. Within the last 200 years they have been turning sandy beaches into cobble beaches. Later on our walk through the island we began to find the interesting striped snails which we didn’t see much of on the shore, feeding on plants and the barks of trees. I was later able to identify the specific tree where we found the most as suemack trees.

Question:
How did the snails get a perfectly drilled hole in their side?
This hole is produced by a moon snail which uses its radula (tongue) which consists of razor like teeth to eat the meat which it finds inside of other snails, scallops, oysters and mussels.

Question:
What do you snails need to live?
Moisture, they eat plants and another vegetation, algae and plankton.

Question:
How did the colorful, striped species of snails get here?
After doing some research it is clear that these snails came to the Northern Atlantic by birds who brought them from Europe and other areas centralized around Europe. There are number of such species but a few examples are the Helix aspersa and Helix pomatia.

We then moved on to the other side of the island to the tidal pool where we began looking at small greenish crabs. After seeking further for these crabs we found that they tend to live under rocks and were then quickly able to find a very large amount of them.
It appears the stripes of the snails tend to fade when they are no longer living.

Question:
What types of crabs are these and where did they come from?
My research has led me to believe that these are the European green crab (Carcinus maenas) also known as ‘the green crab’ which is native of Europe and has now invaded both shores of North America.

Nick Pinheiro