Invasive SpeciesAsian shore crab

Hemigrapsus sanguineus
NOT FOUND by 2018eaf
Falmouth Maine
ID Confirmed
Quality checked by Eliza B
Peer reviewed by
Field Notes
On Thursday, October 9th, 2018, half of my grade took a field trip to Mackworth Island, on the coast of the Atlantic Ocean. It was a cloudy day with temperatures in the lower 60ºs. We were looking for invasive coastal species from the shoreline to the high tide line. We were set up in a transect, with a marker every 10 meters. There were about 11 other groups with their own section on the shoreline. I was specifically assigned to find the Asian shore crab. Other members in my group were assigned to different types of crabs, periwinkle, and rook weed/ knotted wrack.The whole shore was covered in Rockweed and Knotted wrack on top of many rocks and sand. It was very slippery. In order to find species, you had to lift up the Rockweed and Knotted wrack. I did not find any Asian shore crabs, however there were a couple people from seperate groups who found one. We only found invasive Green crabs. We found around 20. This is causing the survival of the other crabs to be very difficult. We found many common periwinkles (invasive) and smooth, but no rough periwinkles or Rapa whelks. The absence of specific species in our area proves that the invasive species are taking up the resources needed for survival in our specific area.
Supporting Evidence
Photo of my evidence.
The Asian shore crab has 3 spines on the outside of each eye, whereas this green crab has 5 spines.
Photo of my evidence.
The shape of an Asian shore crabs carapace is very square like, and the shape of this green crab is more pentagon like.
Photo of my evidence.
The Asian shore crab has a fleshy bulb-like structure in between the pinchers, whereas this green crab does not.
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: 
Photo of our sampling method.
Place Studied
We’re sorry, JavaScript is required to view the map. If JavaScript is you may wish to upgrade to a newer browser in order to view this map.
Map this species
N 43.689722 °
W -70.226944 °
Observation Site Information
A photo of our study site.
Coastal - Rocky intertidal
Trip Information
2018 Mackworth Coastal
Trip date: 
Thu, 2018-10-04 07:26
Town or city: 
Falmouth Maine
Type of investigation: 
Species Survey
Time of low tide: 


Very nice use of visual aids!!