Invasive SpeciesGreen crab

Carcinus maenas
FOUND by THE Happy GINGERS 2
2011-10-05
Falmouth
ID Confirmed
Quality checked by Ms H
Peer reviewed by Sean and Faraz
Field Notes
Originally, we were meant to find the Asian Shore Crab, but unfortunately we were unable to. We found this very odd, considering that the Asian Shore Crab is an invasive species, and therefore should have a high population. Instead of the Asian Shore Crab, we decided to look for the Green Crab, which we found. We are sure we found the Green Crab, because the crab we found had a carapace that was about 10 cm wide, and it had five spines on the outside of each eye. The shell was shaped like a pentagon and was a dark green color with white patterns and coloring. The crab was very fast and difficult to catch, with thin, pointy claws that had extremely sharp tips. We were surprised that the crab we found was green, considering that only 5% of adult Green Crabs are actually green. We found our crab under a large rock covered in gooey seaweed in the intertidal zone. We could smell the salty ocean air and hear the waves crashing on the shore. The only problem we ran into was trying to catch the crab, it was fast!
A sketch of our study site.
Supporting Evidence
Photo of my evidence.
The crab we found has a pentagon shaped carapace that is about 10 cm wide. It is green with with white patterns.
Photo of my evidence.
When we tried to catch our crab, it was extremely fast and difficult to catch. The crabs claws were thin and pointy with sharp tips.
Photo of my evidence.
The crab we found had five spines on the outside of each eye.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Carcinus maenas
Common name:
Green crab
Is it alive?: 
All alive
Count of individuals: 
1-10
Coverage: 
Less than 1/4 covered
Reproduction: 
Eggs (animals)
How big is it?: 
5 - 10 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
Latitude: 
N 43.732060 °
Longitude: 
W -70.204750 °
Observation Site Information
A photo of our study site.
Habitat: 
Coastal - Rocky intertidal
Trip Information
Name:
Eagles Falmouth Town Landing
Trip date: 
Wed, 2011-10-05 10:15
Town or city: 
Falmouth
Type of investigation: 
Species and Habitat Survey
Ecosystem: 
Coastal
Watershed: 
Presumpscot
Time of low tide: 
Wed, 2011-10-05 12:30
Habitat Observations
Species diversity: 
6 different species
Evidence of vectors: 
Boats
People
Water temperature: 
16.0°C
pH: 
7.3
Dissolved oxygen: 
7.7mg/L
Salinity: 
29.3ppt

Comments

That's great that you noticed the shape of the shell and the number of spines. Those are the best ways to identify these crabs.