As Earth warms, species around the world—Adélie penguins, earthworms, gray snapper, pin oaks—are shifting into habitats once too cold for them. One such "climate migrant" is the Atlantic mud fiddler crab Minuca pugnax. Historically found only as far north as Cape Cod, this saltmarsh dweller has now been seen in southern Maine, 75 miles farther poleward.