Invasive SpeciesRapa whelk

Rapana venosa
NOT FOUND by beachwalkers
2014-10-28
Cape Elizabeth Maine
Not Yet Reviewed by Expert
Quality checked by Pp
Peer reviewed by JD
Field Notes
We were at Crescent Beach on October 28th, 2014 to search for the rapa whelk, an invasive mollusk. We used a species ID card from Vital Signs to look for the rapa whelk. It was a cloudy, grey, autumn day and 53°F. We heard the wind and the waves. We saw the rocky coast of Maine. We could smell seaweed and fresh air. We were surprised because there were a lot more mollusks at the beach than I had expected. We were also surprised that some of the mollusks looked so similar to others and some looked so different from others. One problem we ran into was not being able to tell wether the species we found was a rapa whelk or not. One species we found had a small hint of orange on the aperture of the shell, but it was not as deep of an orange as the pictures on the Vital Signs rapa whelk ID card.
A sketch of our study site.
Supporting Evidence
Photo of my evidence.
The species we found was cone shaped. According to an "ID Confirmed" Vital Signs posting, this is how the dog whelk is shaped. The Vital Signs rapa whelk ID card says that the rapa whelk is shaped more like a softball. The aperture on our whelk is white colored while the aperture of the rapa whelk is bright orange. So our whelk cannot be a rapa whelk.
Photo of my evidence.
The mollusk we found had a long, pointed spire. The Species ID card, states that the Rapana venosa has a short spire. The rapa whelk also has knobs on the shell and our whelk does not.
Photo of my evidence.
The mollusk we found had a creamy brown colored shell. By the descriptions of Wembury Marine Centre, this is what the dog whelk's shell looks like. According to the Vital Signs rapa whelk ID card, the rapa whelk has a reddish-brown shell. The dog whelk also has a shell that is about 3 cm. long while the rapa whelk shell can get up to 16 cm. long.
Species Observation: Species Looked For
Did you find it?: 
I think I did not find it
Scientific name:
Rapana venosa
Common name:
Rapa whelk
Sampling method: 
Just looking around
Photo of our sampling method.
Place Studied
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Map this species
Latitude: 
N 43.562159 °
Longitude: 
W -70.219330 °
Observation Site Information
A photo of our study site.
Habitat: 
Coastal - Rocky intertidal
Trip Information
Name:
Kettle Cove (CEMS 7th Grade)
Trip date: 
Tue, 2014-10-28 09:22
Town or city: 
Cape Elizabeth Maine
Type of investigation: 
Species Survey
Ecosystem: 
Coastal
Watershed: 
Presumpscot
Time of low tide: 
Tue, 2014-10-28 08:25

Comments

Hi Beachwalkers,

Great job! I really love how many different sources and how much evidence you used to come to your conclusion that this is not rapa whelk. I think it particularly awesome that you were able to use other student's Vital Signs data to help determine what species this was.

You've certainly convinced me you did not find invasive rapa whelk and I've nominated your observation to the Best Of Vital Signs.

Keep up the great work and happy observing!
-MB