Native SpeciesSmooth periwinkle

Littorina obtusata
FOUND by msk_rockcrab3
ID Confirmed
Quality checked by mdenniston
Peer reviewed by msk_rockcrab2
Field Notes
The day the we traveled to Kennebunk Beach for our vital signs trip it was fairly windy. The wind didn't really effect anything but my filling out of paper work. The water was your typical May in Maine temperature but nobody really minded. It was very overcast and it made it somewhat hard to see under the water.
Supporting Evidence
Photo of my evidence.
The photo shows the contrast between a smooth periwinkle and a common periwinkle. One of the most prominent features of the smooth periwinkle is its bright yellow color. As you can see the common periwinkle is a dark brown color and not the yellow color. Truly this is one of the best ways to tell the two apart (just at a glance.)
Photo of my evidence.
As you can see in the picture the Common Periwinkle (brown) and the Smooth Periwinkle (yellow) have two different point structures. The Common Periwinkle has a pointier tip while the Smooth Periwinkle has a smoother, rounder tip. This is perhaps the second best way (second to the color difference) to tell the two Periwinkles apart.
Photo of my evidence.
This picture shows the two Periwinkles (middle and far right) next to a Dog Whelk (far left). You might be able to see that the openings where the snail lives are different shapes. The Smooth Periwinkle has a very small round opening. The Common Periwinkle has a slightly larger oval opening. And finally the Dog Whelk has an even larger oval opening with a lip or groove at the bottom. This is definitely the third best way to identify a Smooth Periwinkle from other snails and periwinkles.
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?: 
All alive
Count of individuals: 
Eggs (animals)
How big is it?: 
0 - 2 cm
Is it male or female?: 
Can't tell
Sampling method: 
Quadrat (user-placement)
Photo of our sampling method.
Place Studied
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Map this species
N 43.344160 °
W -70.486470 °
Observation Site Information
A photo of our study site.
Coastal - Rocky intertidal
Trip Information
Kennebunk Beach
Trip date: 
Fri, 2013-05-17 11:00
Town or city: 
Type of investigation: 
Species and Habitat Survey
Time of low tide: 
Fri, 2013-05-17 10:58
Habitat Observations
Species diversity: 
36 different species
Evidence of vectors: 
Ocean tides
Water temperature: 
Dissolved oxygen: 


This is one of the best observations I ever remember seeing. Such great evidence and reasoning! This definitely belongs on the best of page.

-The VS Team