The first sighting of the Asian shore crab in the United States was at Townsend Inlet, New Jersey, in 1988. Though the source is unknown, it is likely that the crabs were discharged as larvae from the ballast water of a cargo ship.

First appearing in New England in the 1860s, periwinkles are now found along the coast wherever there’s hard substrate from Labrador to Maryland and along the West Coast.

Since the green crab was first recorded off southern Massachusetts in 1817, it has been hard to ignore. A few minutes of rock-flipping in Maine can turn up dozens of them, brandishing their claws as they retreat to the crags.

With primitive lungs, sharp teeth, and a flattened snout, snakeheads arrived in Maryland in 2002. They were soon dubbed Frankenfish, but that hasn’t stopped bowhunters and anglers from searching out the invasive fish.

You look out over your lawn and curse. The dandelion is back again, doing what it does best: invading. And yet it’s so common now that you may be surprised to learn it’s not a native species—it’s one of the 2,000 or so herbs brought over by European settlers.