1. True or False: European green crab are always green?

False!

2. Hemigrasus sanguinues is the scientific name for which of these crabs: the European green crab, the Asian shore crab, Atlantic rock crab, Jonah Crab, or the blue swimmer crab?

The Asian Shore Crab

3. Please draw a picture of the green crab and list the colors it could be? Do the same for the Asian shore crab.

http://www.uaf.edu/seagrant/nosb/papers/2004/homer-crabs.html    www.bcc.ctc.edu/lmc/plunkett/redrock.htm

The invasive green crab has 5 teeth while the native rock and on the right picture, the jonah  or rock crab both have 9 teeth! These two crabs are tough to identify, that is why it is good they are both native and misidentification is not as damaging as it is for mistaking an invaisve as a native, or Asian for a European green crab.

4. How many teeth does the green crab have on each side of its eye? How many for a Asian Shore Crab? How many for Rock Crab? Jonah Crab? Which species are native to the Atlantic coast of North America and which ones are invasive to this area?

The invasive green crab has 5 teeth on each side of the eye.

The invasive Asian shore crab  has 3 teeth on each side of the eye.

Jonah and rock crabs are both native to the Atlantic coast of North America and BOTH have 9 teeth.

5. How many crabs were shown in the photo session? Please name the crabs?

Green, blue, rock, jonah, and Asian shore crab.

6. How do you tell the difference between a male crab and a female crab green crab? Asian shore crabs? Rock crabs?

This is done by taking the crab and looing on its underside for the shape of the abdomen (tail flap). The males have narrower abdomen that looks like the shape of a lighthouse. While the female has a wider and rounder abdomen.

7.  List from the the invasive speices of crab from smallest to largest adults?

Asian shore crab is smaller than the green crabs

8. What is the carapace width measurement? Why might it be important?

It is an indicator of size and it will allows us to know if they are, on average, larger or smaller in their invasive range. Invasion ecology predicts that they will be larger but I want to see if this is true.

9. Name one example of economic and non-economic damage caused by invasive crabs.

These invasive crab species have caused the economic collapse of shellfish industries in their path. For non-economic (ecological / environmental) damage, the invasive crabs has displaced native crabs to subtidal areas and reduced their abundance.

10. Is this crab a male or female?

Male. 

11. What are the sexes of these two crabs?

On the left is a male and a female on the right.

12. What is the species and sex of this crab?

This is Carcinus maenas, a European green crab! We can not tell if it is a male or female since we have not turned the crab over and examined the size and shape of its abdomen. There is no other way!