Invasive SpeciesAsian shore crab

Hemigrapsus sanguineus
NOT FOUND by teamgreen
ID Confirmed
Quality checked by za,cs,in
Peer reviewed by pb
Field Notes
There were times during our crab hunt when the sun peaked out and other times when it was misty. It felt slightly muggy and the air was wet and heavy, with a light, cool breeze. We started at low tide. We faced challenges such as climbing over slippery rocks and seaweed. We found many barnacles on the rocks and some of the crabs' carapaces. The barnacles made moving many of the rocks difficult. We collected a surprising total of 326 crabs on the school's 6th visit. Once again this year, we had 10 transects. The average amount of crabs per transect was 32.6 crabs, however one group collected 80 crabs.
A sketch of our study site.
Supporting Evidence
Photo of my evidence.
We looked for the hemigrapsus sanguineus but we did not find it. The asian shore crab has light and dark banded legs. This crab does not have light and dark banded legs.
Photo of my evidence.
The Asian Shore Crab's carapace is shaped almost like a square. As you can see this crab doesn't have a square carapace, it has a pentagonal carapace.
Photo of my evidence.
This picture shows a crab with five spines from each eye to the widest point on the crab's carapace. The Asian Shore Crab has three spines on each side of it's eyes. This is further evidence that we don't have any Asian Shore Crabs. We believe we have a Green Crab, Carcinus maenas.
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: 
Time search
Photo of our sampling method.
Place Studied
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Map this species
N 44.433110 °
W -68.940990 °
Observation Site Information
A photo of our study site.
Coastal - Beach or dune
Trip Information
Moose Point State Park
Trip date: 
Mon, 2011-10-03 07:31
Town or city: 
Type of investigation: 
Species and Habitat Survey
Eastern Coastal
Time of low tide: 
Mon, 2011-10-03 10:04
Habitat Observations
Species diversity: 
9 different species
Evidence of vectors: 
Paved road
Walking trail
Water temperature: 
Dissolved oxygen: 


Over the last 6 years the students from our school have collected, measured, and determined the species of 2060 crabs at Moose Point State Park in Belfast. The average # collected was 343.3 per year. All 2060 crabs were checked carefully for species identification and gender. The protocol is the same year to year. All of these crabs were green. Some students think the numbers found will decrease a little,since that has been the trend from 2009-2011,others think it will stay close to the average of 343.3. As long as we stay in the intertidal zone, we believe we will find only green crabs.

Nice detailed description - you captured all of the important features of these crabs.

Wow! This is an impressive observation, and an impressive transect study! Of all of the 326 crabs you found, were they ALL green crabs, or did you find some natives too?

It's great that you now have 6 years of data. Based on your long term dataset, what do you predict next years' students will find? Same species? Same amount?