Invasive SpeciesGreen crab

Carcinus maenas
FOUND by Krabby Killers
Cape Elizabeth
ID Confirmed
Quality checked by mr p
Peer reviewed by TG and GB
Field Notes
While looking for a Green Crab on Kettle Cove it was in the middle of low tide, it was windy and cloudy, and the wind direction and speed was 15 miles per hour south. There were many other species of crab, but Green Crab's were the most common. The crab that we found was absolutely a Green Crab because it had the identified factors that will follow. Green Crab's has very skinny looking claws but sharp ends. Our Green Crab that was found had the same identifying factors, but the end of the claws were really skinny so they looked like a point. Green Crab's color is a big identifying factor of the Green Crab. Green Crab's can be red, green, or brown. There were many Green Crabs on Kettle Cove were green but many had a darker brown on top of their shells. The last identifying factor that was found that was really useful that was used to identify the Green Crab is that the spines are located on each side of the shell. A Green Crab has exactly 5 spines on the outside of each eye, that is an identifying factor because it is easy to tell apart from other crabs that look like it.
A sketch of our study site.
Supporting Evidence
Photo of my evidence.
One way to tell if you found the Green Crab is to look at the spikes on the outside of each eye. A Green Crab always has five spikes on the outside of each eye. If you think you found a Green Crab but it doesn't have exactly five spikes on the outside of the shell, you have not found a Green Crab. On the Vital Signs ID Cards these are what they say you need to look for to identify this crab.
Photo of my evidence.
A shell is a very important identifying factor of the Green Crab. The way that you can tell the difference between other crabs and the Green Crab is that the Green Crab's shell has a pentagon-like shape. The crab has five spikes, there are other crabs that have five spikes but this is the most popular, and easiest to find. I was able to identify this crab by all of the identifying characteristic on the Vital Signs ID Cards.
Photo of my evidence.
The claws of a Green Crab are very different than other crabs, that look very similar. The claws look very skinny and breakable but truth be told they are very strong and dangerous to other small sea animals. When you reach the top of the claw it starts to turn a dark brown, and the tip gets very sharp. I learned about the claws and all of these factor from the Green Crab ID Card on Vital Signs.
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 43.561373 °
W -70.218542 °
Observation Site Information
A photo of our study site.
Coastal - Rocky intertidal
Trip Information
Kettle Cove 2017
Trip date: 
Tue, 2017-10-24 09:00
Town or city: 
Cape Elizabeth
Type of investigation: 
Species Survey
Time of low tide: 
Tue, 2017-10-24 08:30


Very nicely detailed evidence!