Stowaway Species Interactive

On any given day, as many as 5,000 invasive species are taking an ocean voyage via ballast water. The environmental and economic impacts can be devastating. Zebra mussels invaded the Great Lakes via ballast water in the late 1980s. To date, they've done more than $1 billion in damage by blocking intakes to power plants and disrupting aquatic food webs.

The U.S. Coast Guard proposed new rules last August designed to stop these bioinvasions. To comply, shipping companies need to adopt new technologies, such as straining out organisms with microfilters or zapping them with ultraviolet light. Above, see how species are able to spread across the globe via ballast water and the damage that some of the worst have done.

Produced by Joseph Lin based on an illustration by Arthur Mount