Invasive SpeciesAsian shore crab

Hemigrapsus sanguineus
NOT FOUND by ClimateChange12012
2012-09-20
Cape Elizabeth
ID Confirmed
Quality checked by Keirstan F.
Peer reviewed by Danae S.
Field Notes
We placed our quadrat in a tidal pool about three yards away from the receding rocky intertidal waters. In order to observe and record some species we were required to disturb the rock and seaweed formations within the quadrat. Both the Rock Weed and Chain Sea Squirt were found growing on the rocks. The sea squirt was predominate on the underside of the rocks while the rock weed was growing on top of the rocks. Multiple crabs were found, both dead and alive, but non were the Asian Shore Crab.
Supporting Evidence
Photo of my evidence.
Multiple crabs were found, but this particular crab does not have a square shape, or any rings present on its legs.
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
Latitude: 
N 43.560800 °
Longitude: 
W -70.220170 °
Observation Site Information
A photo of our study site.
Habitat: 
Coastal - Rocky intertidal
Trip Information
Name:
Kettle Cove
Trip date: 
Thu, 2012-09-20 09:00
Town or city: 
Cape Elizabeth
Type of investigation: 
Species Survey
Ecosystem: 
Coastal
Watershed: 
Presumpscot
Time of low tide: 
Tue, 2011-09-20 08:30

Comments

Submitted by ClimateChange12012 on Wed, 2012-09-26 07:48.

Response to Sniffly

We found a variety of crabs, but unfortunately a few were dead specimens. Most within the immediate region of the quadrat looked like the one in the picture, there were no green ones to be found.

Others in our class did find the Asian shore crab, and lots of them! Our quadrat was placed incredibly close to the open water, while the Asian shore crabs were found closer to the sandy beach, on rocks that were heavily occupied with seaweed. In the area where we were, it would have been hard for the crabs to multiply because the tide was constantly pulling the water of the tidal pool back into the ocean. The area where they found the crab was more secluded from the lapping tides.

Submitted by sniffly salamander on Wed, 2012-09-26 09:12.

It sounds like you have some

It sounds like you have some great observations and hypotheses about where crabs will thrive or not thrive. Will you have any opportunity to set up some studies to test those ideas more? What kind of data could you use to back up those predictions?

Thanks for sharing your observations,
~sniffly

Submitted by Crab Lady on Tue, 2012-09-25 21:23.

I agree with Sniffly that

I agree with Sniffly that this looks like a juvenile Jonah or rock crab. It tough to tell which based on this photo. Good luck with your field work!

Submitted by sniffly salamander on Mon, 2012-09-24 13:34.

I'm curious how many crabs

I'm curious how many crabs you found and if they all looked like this one. I'm not a crab expert, but this one looks like a rock or jonah crab. It's hard to tell to a crab ID novice like me :) . Did you find green crabs, too?

I'm also curious about what might have been different about where you were looking and where your classmate that did find Asian shore crab was looking. Maybe there was nothing special and different about the spots, but then again, maybe there was something. Could be a neat question to explore.

Nice work out there!

~sniffly