Invasive species have a bad reputation -- from plant-choking vines to nest-usurping birds, they're often rightly blamed for crowding out native flora and fauna and altering the environment they invade.
But that's nothing, compared to the 10 species on this list: They are so aggressive, they've actually changed the world as we know it.
These pink creepy-crawlies might not seem like much to the casual eye, but earthworms
just may be the most important invasive species in history. History scholar Christopher Lloyd points out that Charles Darwin considered the earthworm the most influential creature on the planet.
As earthworms expanded to land after descending from sea worms, they provided essential soil services like ventilation and fertilization. "Wherever earthworms plow, people thrive," Lloyd told National Geographic. "Wherever worms perish, societies collapse."
However, considering our influence on habitats, this might not actually be a good thing.
Photo: goosmurf/Creative Commons