Invasive SpeciesCommon periwinkle

Littorina littorea
FOUND by msk_limpet2
ID Confirmed
Quality checked by mdenniston
Peer reviewed by msk_rockcrab1
Field Notes
Today is a fairly nice day. The wind is blowing, and the sun is hidden by some clouds. It's not to warm, the temperature is about 50 degrees and there is a need to wear a sweatshirt. There are small waves crashing far out in the sea. People look happy to be here and there are lots of smiles on people's faces ready to find new species and learn.
Supporting Evidence
Photo of my evidence.
My first piece of evidence is a common periwinkle being compared to a dog winkle. They are flipped over on their backside so you can see the snails muscular foot. The thing that shows the difference between the two is the shaping of the hole the different species sticks out of. The common periwinkle on the right has a hole shaped like a circle. The dog winkle is different and has a more thin oval shaped hole. The common periwinkle's hole to get out of their shell is also an even circle with no grooves whereas you can see a little groove at the top of the dog winkle's shell.
Photo of my evidence.
The common periwinkle's shell like the periwinkle I found has a pointed tip on the top of the shell. The picture of the one I found also has a pointed tip on the top of the shell. The shell is smooth until the top where it comes to the top in a fairly sharp point that overtime wears down.
Photo of my evidence.
This is a Common Periwinkle compared to a smooth periwinkle. The color is another thing that separates Common Periwinkles from the rest. Usually the common periwinkle is a darker color. Like the one in the picture a light gray brown color is the most common for a common periwinkle. The smooth periwinkle is usually olive green to bright yellow in color. The different shades that the different kinds of snails in are another way to verify their species.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Littorina littorea
Common name:
Common periwinkle
Is it alive?: 
Count of individuals: 
How big is it?: 
2 - 5 cm
Is it male or female?: 
Can't tell
Sampling method: 
Quadrat (user-placement)
Time search
Photo of our sampling method.
Place Studied
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Map this species
N 43.344160 °
W -70.486690 °
Observation Site Information
A photo of our study site.
Coastal - Rocky intertidal
Trip Information
Kennebunk Beach
Trip date: 
Fri, 2013-05-17 10:00
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: 
Water temperature: 
Dissolved oxygen: 


Well done with this post! I really like the comparisons between the different intertidal snails. Your clear observations distinguish the different intertidal species very nicely.

Great job and keep up the good work!!

Cool how you compared the common periwinkle to other snails to support your case!! Very convincing :)