Invasive SpeciesGreen crab

Carcinus maenas
FOUND by VectorEel
ID Confirmed
Quality checked by Teacher
Peer reviewed by Whole class
Field Notes
It quiet, overcast day with occasional drizzle and no breeze. We recorded the air temperature as being 19ºC. Although the trip was part of our water testing and oceanography unit, we also spent time looking at the life in the study area. We were excited to find eels, frogs, crabs, fish, and a lot of algae growing on the river bottom and rocks. Our water test results were: Air temp(20ºC), Water temp(19ºC),Substrate temp (13ºC), pH(7), DO(6ppm), Salinity(0 ppt), Phosphates (4 mg/L), Nitrates(0 mg/L), Iron (suspect, <1 mg/L), Chlorine (not detectable), Turbidity(0 JTU, clear), Wind(0 mph),Tide (low, going out) E. coli & coliform bacteria (+ present). We had fun, especially when the owners got us drinks!
A sketch of our study site.
Supporting Evidence
Photo of my evidence.
The crab had five spines on each side of the eye. It's shell shape almost fooled us into thinking it was an Asian shore crab, but we looked closer. It was brownish green and it was aggressive, but we were lucky it was very small.
Photo of my evidence.
We lost some photos in the camera and many were fuzzy. But we did find the same type of crab at the mouth of the river near the rocky beach near the Cape Neddick campsite. These were much bigger than the small ones we found on the marsh grass (I think the teacher said the estuary is a nursery for many animals).
Photo of my evidence.
The big crab was found in this rocky intertidal habitat while the first, small green crab was found up river about 1 to 2 miles. This was a tidal river. Our equipment and survey forms are in the picture with my team in the back.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Carcinus maenas
Common name:
Green crab
Count of individuals: 
Less than 1/4 covered
How big is it?: 
0 - 2 cm
Is it male or female?: 
Can't tell
Sampling method: 
Just looking around
Quadrat (user-placement)
Time search
Photo of our sampling method.
Place Studied
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Map this species
N 43.193381 °
W -70.615931 °
Observation Site Information
A photo of our study site.
Freshwater - In a stream or river
Trip Information
Cape Neddick River
Trip date: 
Wed, 2012-05-30 08:30
Town or city: 
Type of investigation: 
Species and Habitat Survey
Cape Neddick River
MIDAS Code: 
Habitat Observations
Species diversity: 
4 different species
Evidence of vectors: 
Paved road
Walking trail
Small boats coming up to go eeling.
Water temperature: 
Dissolved oxygen: 


Nice work, and a wonderful drawing too!