Invasive SpeciesAsian shore crab

Hemigrapsus sanguineus
ID Confirmed
Quality checked by Go science
Peer reviewed by
Field Notes
I am happy because we were able to move rocks and seaweed and locate many crabs. We didn't find Asian shore crabs, but we did find 20 plus green crabs and two native rock crabs. It was unusual that we found native crabs because we were the only group that found a species of native crabs. We were right next to the water's edge in 60 degree with a little bit of cloud cover. The air was fresh with a cooling hint that a jacket couldn't fix. It was very a very rocky area, this made it so we had to be very careful not to fall, but this also created opportunities for a wet cool space to find crabs. We started by just moving seaweed at first, but we weren’t finding anything so we started picking up and moving around the biggest rocks we could find. I am surprised that we found so many crabs but I am also surprised that we didn't find any Asian shores because in years past there was a finding of Asian shores by every group, this year not so much. We put our quadrant over a very rocky and seaweed covered area which later became a problem because we had to move the rocks around to find any crabs at all, but after we started moving the large rocks we came upon a threshold full of green grabs and two rock crabs that we immediately set free because they are native crabs that are not harmful to the environment of Maine. Also during our studies we pulled up a crab trap that the other two days had been marking crabs found and reloading the traps, on the third day the day our group went, we caught a crab that was marked with yellow nail polish. Questions or problems I ran into are that we were unable to find any Asian shore crabs that is a problem because we went out looking for Asian shore crabs and we were not able to find them. Although it was a little disappointing not to find this invasive species, it is good for our Maine ecosystem.
Supporting Evidence
Photo of my evidence.
Our evidence to why this crab is not a Asian shore crab is that you can see the five spines and the pentagonal shape of its shell, meaning that the crabs we found were green crabs.
Photo of my evidence.
Our evidence shows we found many green crabs. The starting size of the green crabs were about the size of a quarter to 5 centimeters. We found this by measuring from the first spine to the fifth, which indicates that these crabs are green crabs, not Asian shores because of the five spines.
Photo of my evidence.
A different species we found was a native rock crabs. These crabs are very good to the environment. They also eat invasive species like the green crab and Asian shore that come into our waters. We found two of theses native rock crabs in the same spot located under a rock in a running stream, which really surprised us to find them together.
Species Observation: Species Looked For
Did you find it?: 
I think I did not find it
Scientific name:
Hemigrapsus sanguineus
Common name:
Asian shore crab
Sampling method: 
Quadrat (user-placement)
Photo of our sampling method.
Place Studied
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Map this species
N 43.784992 °
W -69.721920 °
Observation Site Information
A photo of our study site.
Coastal - Rocky intertidal
Trip Information
Reid State Park river
Trip date: 
Fri, 2017-10-27 10:00
Town or city: 
Type of investigation: 
Species Survey
Time of low tide: 
Thu, 2017-10-26 11:08


Great work, Eel, noting the key characteristics of these crabs!