Invasive SpeciesAsian shore crab

Hemigrapsus sanguineus
NOT FOUND by pbernhardt
2010-09-30
Belfast
ID Confirmed
Quality checked by Tessa, Maggie, Hannah, Kathryn
Peer reviewed by Hannah, Kathryn
Field Notes
Our trip started with a cloudy, foggy day. We emerged from the bus to see a rocky intertidal zone covered in seaweed and tide pools. After breaking up into our transect groups, we gathered up our materials for catching, and measured our 10 x 2 meter transects. We practiced catching the crabs outside our transect zones before the real hunt began. The official hunt was 20 minutes in length. After the 20 minutes, we collected our data (we measured the carapaces, found their gender, and determined their species). We collected a total of 328 crabs and all were green.
Supporting Evidence
Photo of my evidence.
We didn't find what we were looking for because this crab, like the other ones we found, has five spines between the eye and the widest part of the carapace, and Asian shore crabs only have three.
Photo of my evidence.
Asian Shore crabs have a square carapace and this green crab has a shield or hexagonal shaped carapace .
Photo of my evidence.
Asian shore crabs have obvious lighter bands on their legs and green crabs do not. This crab has a variation of light and dark shades on it's legs, but not true banding.
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
Transect
Photo of our sampling method.
Place Studied
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Map this species
Latitude: 
N 44.431600 °
Longitude: 
W -68.941960 °
Observation Site Information
A photo of our study site.
Habitat: 
Coastal - Rocky intertidal
Trip Information
Name:
Moose Point State Park
Trip date: 
Thu, 2010-09-30 09:40
Town or city: 
Belfast
Type of investigation: 
Species and Habitat Survey
Ecosystem: 
Coastal
Watershed: 
Eastern Coastal
Time of low tide: 
Thu, 2010-09-30 09:50
Habitat Observations
Species diversity: 
2 different species
Evidence of vectors: 
Paved road
Dirt road
Walking trail
People
Recent disturbance
Possible lobstering boats that we did not see.
Water temperature: 
20.3°C
pH: 
7.9
Dissolved oxygen: 
5.5mg/L
Salinity: 
25.0ppt

Comments

Your observation has some wonderful photos! Actually, every photo is wonderful, and spot-on to what was requested. I'm convinced by your evidence images, I know where you were looking from your site image, and I know how you looked from your method image. Well done.

And great to have data from a new location!

Thank you so much.

Thank you for your input and encouragement. We appreciate it! Just thought we would let you know we collected 32.8 crabs per transect on average; we had 10 transects. The majority were male and all were green as previously stated. Before the timed transect hunt began, one group found a dead jonah crab in the intertidal. We could not count it though since it was not in a transect.

You're right, this is a not an Asian shore crab. You did a very thorough job describing this crab. Just so you know, juvenile green crabs can have banding on their legs that look a lot like the banding on Asian shore crabs. People often confuse a juvenile green for an Asian shore crab because of this. But, if you count the spines next to their eyes (as you did here), you will always know which crab you have!

This is an incredible observation! It's clear you did a careful, thorough job with your Quality Check and Peer Review process. Nice to have many brains taking this on!

...and (invasive or not) what a handsome crab you found!