Invasive SpeciesGreen crab

Carcinus maenas
FOUND by Carowland52
South Portland
ID Confirmed
Quality checked by Sr
Peer reviewed by Sr
Field Notes
I am out collecting data to locate the invasive green crabs. I am supporting the green crab mission, which is working to find out how the populations of green crabs are changing across the coast of Maine. It was a warm evening and sunny during my field study. The tide was about half way out. I think the answer to the question posed in the mission statement is that green crab populations are growing. I say this, because they have few to no predators on the coast of Maine, and there is no market for green crabs so no one is harvesting them.
Supporting Evidence
Photo of my evidence.
The species that I found had five spines on the outside of each eye. Species native to Maine have eight to ten spines, while invasive species, other than the green crab, have either four or less. The green crab is the only one with five spines.
Photo of my evidence.
The species I found has thin claws with sharp tips, the same as a green crab. The native species have large, bulky claws.
Photo of my evidence.
The species I located had a pentagon shaped carapace, which is the shape of a green crab’s carapace. With other crab species the anterior end of the carapace is more rounded, with not as clear sections.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Carcinus maenas
Common name:
Green crab
Sampling method: 
Just looking around
Photo of our sampling method.
Place Studied
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Map this species
N 43.646863 °
W -70.226336 °
Observation Site Information
A photo of our study site.
Coastal - Rocky intertidal
Trip Information
Trip date: 
Thu, 2017-06-15 19:30
Town or city: 
South Portland
Type of investigation: 
Species Survey
Time of low tide: 
Thu, 2017-06-15 22:00


Great detailed description of this crab!

Hi Carowland52 - Did you see many green crabs while you were looking around? Did you see any native species or any other invasive species of crabs?