Native SpeciesSmooth periwinkle

Littorina obtusata
FOUND by Intertidal one
Cape Elizabeth
ID Confirmed
Quality checked by Mrs Moniz
Peer reviewed by Savage fire piglets
Field Notes
Field notes: A thick blanket of fog covered the rocks making it impossible to see to the ocean on that cold October morning. An occasional horn from a passing ship could be heard. You could hear the occasional ouch from an unlucky step on the wet rocks. The crash of waves almost drowns out the happy squeals of people that found their species. The buses roared to life leaving us on the beach and that's when we knew the hunt had begun. Our search was conclusive. Our species was located in an intertidal pool just as the ID sheet said. On Kettle Cove beach, the Periwinkle we chose to study had no inhabitant but the shell itself was good enough to study the physical features. We found many more Smooth Periwinkles but decided to study the first one in the intertidal pool because it had bladder wrack nearby. In our search we only found one inhabitant in it’s shell, this makes us think that the population is dropping perhaps due to the invasion of the Green Crabs. Green Crabs are the main predictors of the Smooth Periwinkle.
Supporting Evidence
Photo of my evidence.
We believe that we have found the Smooth Periwinkle. We think this because of the flat spire (which is a pointed tower on the side of a Periwinkle). The Smooth Periwinkle is the only Periwinkle in Maine that has no point, so compared to the Common Periwinkle it is easily identified. The Common Periwinkle has a point that protrudes outwards but the Smooth Periwinkle is smooth like a pearl. The Smooth Periwinkle also has a smaller spire than the Rough Periwinkle.All these facts can be found at the species ID sheet, and at
Photo of my evidence.
We believe this is a Smooth Periwinkle because of its uniquely tear shaped aperture that is shown in the picture. An aperture is a opening in a shell where the Periwinkle or Crab,is exposed to the air and water.
Photo of my evidence.
This is the Smooth Periwinkle in its natural habitat.The Periwinkle likes to sit in small tide pools and is often covered in water. We found the Periwinkle completely submerged by water. Unfortunately the species was not in its shell but that's where we found the shell. The shell was near some Bladder Wrack seaweed.This is different from the rough periwinkle because it would sit in a upper tidal pool or on the rocks meanwhile the smooth periwinkle has to sit in a lower tidal pool.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Littorina obtusata
Common name:
Smooth periwinkle
Sampling method: 
Just looking around
Photo of our sampling method.
Place Studied
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Map this species
N 43.561483 °
W -70.219153 °
Observation Site Information
A photo of our study site.
Coastal - Rocky intertidal
Trip Information
Kettle Cove Oct 2015
Trip date: 
Tue, 2015-10-20 07:40
Town or city: 
Cape Elizabeth
Type of investigation: 
Species Survey
Time of low tide: 
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