Native SpeciesSmooth periwinkle

Littorina obtusata
FOUND by mdenniston
ID Confirmed
Quality checked by
Peer reviewed by
Field Notes
We are happy because we get to do our research at one of our favorite summer places with our family team. We love exploring among the rocks and we love that our dog gets to be a scientist right along with us! The waves are crashing on the foggy shore and cooked lobster shells lie wedged among the rocks. We hear seagulls calling above the crashing waves as a foghorn blows in the distance. The barnacles make gurgling noises as we walk over them. The air has a moist and salty smell. Walking on the rocks and seaweed was tricky and slippery! We were surprised and a little disappointed that we could only find 2 live crabs, both of them green crabs. We believe there are many rock crabs, Jonah crabs and green crabs here because their shells are common on the rocks, but live ones are very hard to find. Periwinkles and dog whelks are everywhere among the barnacles and seaweed.
A sketch of our study site.
Supporting Evidence
Photo of my evidence.
We found many smooth periwinkles ranging in color from gray to red to yellow. Their shells and whorls were very smooth with a very flat spire that did not come to a sharp point.
Photo of my evidence.
When we turned the smooth periwinkles over, we noticed that the opening of the shell was tear-shaped and the color of the shell around the opening was white or very light colored compared to the rest of the shell.
Photo of my evidence.
When we compared the smooth periwinkle (on left) to the common periwinkle (on right), it was easy to see how much flatter the spire of the smooth periwinkle was.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Littorina obtusata
Common name:
Smooth periwinkle
Is it alive?: 
Some dead & some alive
Count of individuals: 
Less than 1/4 covered
How big is it?: 
0 - 2 cm
Is it male or female?: 
Can't tell
Sampling method: 
Just looking around
Photo of our sampling method.
Place Studied
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Map this species
N 44.428280 °
W -67.911890 °
Observation Site Information
A photo of our study site.
Coastal - Rocky intertidal
Trip Information
Petit Manan Point
Trip date: 
Fri, 2009-07-17 11:30
Town or city: 
Type of investigation: 
Species and Habitat Survey
Coastal Washington and Hancock Drainage
Time of low tide: 
Fri, 2009-07-17 00:14
Habitat Observations
Species diversity: 
30 different species
Evidence of vectors: 
Walking trail
Recent disturbance
Water temperature: 
Dissolved oxygen: 


i love the picutures and the nice information you gave the readers!