Tuesday, March 27, 2012

Invasive Species: Green crab

The European green crab (Carcinus maenas) is also known as the shore crab.
Blue = native range, red = current invasive range, green = at risk
This species is native to the waters off the coast of North Western Europe on down to parts of Northern Africa. It has now become invasive in waters off the coast of Australia, South Africa, Canada, Argentina, and Japan. Many other areas of the world are at risk of invasion. Introduction was through the shipping industry, either through ballast water or fouling organisms.

Many of this species' characteristics makes it an incredibly infective invader. It tolerates a wide range of temperatures, salt levels, and types of habitat. It is an omnivore that will eat just about anything it gets its claws on, including known species from 158 genera at least. It is directly linked to falling numbers of several other species of crab as well as some mollusks. It is even linked to the collapse of the soft-shell crab industry in Nova Scotia and New England. $22 million in damages can be linked to this species in the United States alone. Overall, it has caused decreases in biomass and biodiversity of estuaries where it is found.

This species is currently on the list of 100 World's Worst Invasives at #18.

Images are from Wikimedia Commons under Creative Commons licenses: one, two.


  1. The research course (focused on developing skills rather than discovering something novel) I did the summer before my last year of university focused on the green crab. We are on the east coast, based out of the St. Andrews Biological Station in St. Andrews, NB.

    Housing the little buggers together after collection ended up in them cannibalizing eachother...I was attempting to measure their basal metabolic rate but because they kept eating eachother's legs, the rates I was measuring were closer to published values for metabolic rates after meals.

    I found it highly amusing that I got to cite cannibalism in my paper as a reason for things not working out.

    1. Oh, that's quite an interesting result. And yes, it's always amusing if you get to write about something a little different form the norm. During my final semester I did research on fungus-growing Cyphomyrmex ants, who grow their fungus in "yeast" form on insect frass substrate. I was actually testing for substrate preference, so I literally did the entire thing on the ants' choice of poop. When I presented it, I had a little fun with that. ;)

  2. Yikes. I recently wrote about Chinese mitten crabs, which are another invasive coming in through ballast water. But I didn't know anything about the green crab. Ashley's comment about crab cannibalism is pretty horrifyingly funny.

    1. It's amazing how many invasive species there are out there. I might need to look into the Chinese mitten crab because I don't think I've heard of that species before.