I came from the coasts of the North and Baltic Seas in Europe. Now I’m a bi-coastal resident in the Atlantic and Pacific Oceans. I have been in the Atlantic for almost 100 years, but it wasn't until the 1990s that I reared my ugly head in the Pacific. It’s been easy to adapt to these new environments because I like all sorts of coastal habitats, enjoy a huge temperature range, and can make my way easily in different salinity (salt) levels.

I’ve found so many ways to invade new places. First, when I’m in the larval stage I ride the ocean currents. As a young punk, I take advantage of the tides and currents to move into the upper intertidal zone where I multiply like crazy. Did you know our females can produce up to 200,000 eggs at a time? Some people think it was the strong el Niño currents of 1998 that washed me from the San Francisco Bay in California up to Oregon and Washington.

You humans can be great at aiding and abetting our crimes by moving us around where we don’t belong! When you ship live seafood, like oysters and lobsters, I hide out in the seaweed packing. Sometimes fish farmers accidentally put me into waters where I’ve never been before. Boaters can move me and my gang in bait buckets or boat wells, without realizing what trouble you’re causing. Sometimes people buy me, either as a pet or to use in research. And, when they’re done with me, guess what? They dump me into lakes, streams or ponds and my aquatic neighborhood gets even bigger. Of course, like many other pesky invaders, I’m a stowaway in the ballast water of marine vessels.

If you like Dungeness crab, clams and oysters, BEWARE because I’m a glutton for these tasty morsels. I am such a good predator because I show no mercy. I’m really quick, I can open bivalve shells easily with my claws, and I can’t seem to get enough—sometimes I eat 40 half-inch clams in one day. I also take food that your native fish, crabs and birds would normally enjoy. Sometimes I do a real number on birds because I serve as a host to a marine worm that makes birds sick when they eat me.

Not only do I annoy you people in North America, but I’m also a nuisance to people trying to enjoy the waters of South Africa and Australia.

You have a hard time conquering my many gangs because you can’t use really big weapons, like lots of pesticides, in a coastal area. You’d end up killing a lot of innocent bystanders that belong in those waters. One way to hit me hard is to use the dreaded parasitic barnacle to keep me from reproducing. The larva get inside me and affect my sex organs (of all the sneaky, underhanded tactics). But scientists don’t know whether this control method is safe. Divers can help by learning how to identify me and reporting any new sightings. People need to clean their boats and bail buckets so they don't spread me around.