Invasive SpeciesCommon periwinkle

Littorina littorea
FOUND by stickywhales207
Cape Elizabeth
ID Confirmed
Quality checked by Kris M
Peer reviewed by space adventure squad
Field Notes
At Kettle Cove beach on October 28, 2014, my group attempted to find Litorina littorea or the Common Periwinkle. It was an overcast day with a light breeze. It felt cool near the coast and was low tide. The journey to the rocky intertidal zone was hard because our feet got stuck in mushy seaweed near the water. All of the rocks were wet and covered with seaweed. Upon reaching the beach, my group was surprised by the number of periwinkles. Their population exceeded our expectations. Although there were many periwinkles, not all of them were the Common Periwinkle. As we were examining specimens we had to carefully distinguish them between the Common Periwinkle and a related species called Rough Periwinkle.
Supporting Evidence
Photo of my evidence.
The opening at the bottom of the Common Periwinkle has a white streak the side of the shell. The soft tentacle on the inside has a color like bronze and has horizontal black lines on it as well. On the identification sheet for the Common Periwinkle these features classify this specimen as Common Periwinkle.
Photo of my evidence.
The main difference between the Common Periwinkle and the Rough Periwinkle is the shape of the whorls on the shell. The specimen we collected had flattened whorls which shows that it is Common Periwinkle, unlike the Rough Periwinkle that has deep indented whorls.
Photo of my evidence.
The specimen had a short spire (spiraled end) with a pointed apex (tip). The specimen's lip met the whorl at a < 90 degree angle. On the Vital Signs identification sheet these features classifies this specimen as Common Periwinkle.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Littorina littorea
Common name:
Common periwinkle
Sampling method: 
Just looking around
Photo of our sampling method.
Place Studied
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Map this species
N 43.562003 °
W -70.219526 °
Observation Site Information
A photo of our study site.
Coastal - Rocky intertidal
Trip Information
Kettle Cove Cape Elizabeth
Trip date: 
Tue, 2014-10-28 09:08
Town or city: 
Cape Elizabeth
Type of investigation: 
Species Survey
Time of low tide: 
Tue, 2014-10-28 08:25


Great observation stickywhales! It was easy for me to confirm your finding because of your excellent written and photographic evidence. I especially love your photo of the periwinkle body, it can be really challenging to get a photo of those black lines.

Thanks for posting and happy observing,